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Best Thermal Reflex Sights 2021: Reviews & Guide

Looking for the best thermal reflex sight that can help give a crystal-clear view of your target?

Look no further!

However, if you have a small budget and don’t want to burn a hole in your pocket, you can check out our .
best crossbow scope for night hunting

Thermal reflex sights are incredibly powerful pieces of hunting gear that light the world in front of you. They’re a high-tech means to determine and close on the location of a prey, predator, or potential threat.

These sights allow hunters to see in environments where it would normally be impossible to see anything with the naked eye. They make it easier to locate and confirm a target, allowing you to identify predators, track down game, better spot game, and get eyes on any intruders. Since thermal sights are an active device, hunters can use them at any time during the night or day, when there’s visible light present.

What’s In This Guide?

This buying guide compares and reviews some of the best thermal reflex sights in great detail.

However, if you have a small budget and don’t want to burn a hole in your pocket, you can check out our more affordable thermal scope picks.

5 Best Thermal Reflex Sights

Sig Sauer ECHO3 1-6x
  • Sig Sauer Echo 3

  • Best for Hog Hunting
  • Magnification:
    1 – 6x

  • Battery Life:
    6 hours

  • Weight:
    14.3 oz

  • Resolution:
    320 x 240

ATN Thor 4 Thermal Riflescope
  • ATN Thor 4 Thermal Riflescope

  • Best Budget Thermal Sight
  • Magnification:

  • Battery Life:
    18 hours

  • Weight:
    1.93 lbs.

  • Resolution:
    384 x 288

Armasight by FLIR Apollo Pro 640 Scope
  • Armasight by FLIR Apollo Pro 640 Scope

  • Best Clip-on Thermal Sight
  • Magnification:
    1x Optical, 2x 4x 8x Digital Zoom

  • Battery Life:
    7 hours

  • Weight:
    2 lbs

  • Resolution:
    640 x 512

Trijicon IR Hunter Mk 3
  • Trijicon IR Hunter Mk 3

  • Best for Hunting
  • Magnification:
    2.5x Optical, 8x Digital

  • Battery Life:
    3.5 – 5 hours

  • Weight:
    988 grams

  • Resolution:
    640 x 480

OPMOD Thor LT 3-6X
  • OPMOD Thor LT 3-6X

  • Best Value for Money
  • Magnification:
    3 – 6x

  • Battery Life:
    10 hours

  • Weight:
    1.4 lbs.

  • Resolution:
    160 x 120

1. Best for Hog Hunting: Sig Sauer Echo 3

best thermal scope

Sig Sauer’s latest design, the Echo 3 Thermal boasts advanced BDX technology, helping you shoot your target precisely and accurately. Its compact and innovative design enables you to sit comfortably and view your surroundings with a thermal camera until you find your target.

If you’re looking for the best product for hog hunting, the Sig Sauer Echo 3 thermal reflex sight is the ideal choice.


  • Video recorder allows hunters to capture their hunting experience in video and image format
  • KILO BDX Rangefinder shows the exact size and height of long-distance targets·         
  • 11 color palettes ensure you find your target in every type of weather·         
  • High-quality, 23mm objective lens gives a clear and crisp view of the target


  • Pricier than other models

Our Review

Although the Echo 3 is technically not a conventional “scope,” it’s still a high-performing optic you can attach to your AR when you go hog hunting. If you’re hunting in daylight and don’t need the sight, you can use its quick-disconnect mount to simply remove it, but who wouldn’t love a bit of thermal advantage during the day as well?

The unit boasts a large 10-degree FOV and a 6x magnification. It features the trade-marked LevelPlex Anti-Cant System along with a 0.5-degree scope cant sensitivity, so it can easily withstand heavy use and heavy loads.

If you’re a Sig fan, you might already own Sig Sauer BDX compatible optics, and thankfully, the manufacturers were smart enough to incorporate Bluetooth/Wi-Fi technology into this unit. It further comes with a ton of windage and elevation adjustment travel, minute 0.5 MOA adjustment increments, and numerous reticles to choose from.

Since the Echo 3 is designed for predator and hog hunters, it comes with a motion-activated display feature that powers on when it detects motion. Whether it’s snorts snorting, hoofs hoofing, or ears fluffing against brushes, you’ll be able to see it all with the Echo 3 thermal optic.

Its compact design further allows you to comfortably mount it on rifles of all sizes. It’s also built with IPX-6 rated materials, making the unit waterproof. The Echo 3 uses the VOx LWIR Core as its thermal sensor, which is an uncooled type thermal sensor that will identify the heat signatures in your surroundings.

This sensor has a high resolution of 320x240, so you’ll always get a clear and crisp view of your target. It also has a pixel pitch of 12µm, so you’ll be able to get a close and detailed view of medium-ranged targets. The sensor also has a refreshing rate of 30 Hz, which means that it will refresh the sight picture after every 30 seconds, so you can view your target in real-time and shoot it easily, even if it’s on the run.


The Sig Sauer Echo 3 has a pretty large price tag for such a small and tiny sight, especially since it cannot even be construed as a rifle scope. It also lags behind newer-generation thermal sights in terms of resolution, but you don’t feel that much of a difference when you’re actually using the sight. It’s also not ideal for long-range hunting and is suitable for shorter distances, such as for entry-level hog hunts with a .223 platform.

Bottom line 

The Sig Sauer Echo 3 boasts a durable and sturdy construction, so you can use it in all kinds of weather. Its advanced technology and innovative features help get a clear and crisp image of your target, making the sight perfect for outdoor use. All in all, the Sig Sauer helps you shoot accurately in both night and day time.

2. Best Budget Thermal Sight: ATN Thor 4 Thermal Riflescope

thermal imaging scope

The entire Thor 4 scope series fulfills the demands made by both shooters and hunters. It doesn’t matter whether you prefer to hunt during the night or day time. If you’re looking for the type of detection that puts you at a distance, but allows you to stalk and watch your unsuspecting prey, the Thor 4 is the perfect option.


  • Ergonomic design makes it incredibly easy to find and use the controls.
  • Provides high-definition images and ensures you hit more shots·
  • Comes with a video feature that streams and records at the same time·
  • Wi-Fi and Bluetooth 4.1 are compatible with both Android and iOS·


  • Some quality control problems

Our Review

The ATN Thor 4 384 is basically an ingenious combination of next-generation quality and smart tech. This model is on the lower side of the magnification and price range in the Thor 4 scope series. Since it has low power, its detection range goes to a maximum of 750 meters, while its identification range goes up to 205 meters

A three-year warranty backs the Thor 4, so you don’t have to worry about the durability and reliability. If you’re willing to purchase a budget-friendly thermal sight, you’ll love the clear and crisp thermal imaging. The unit features a dual-core fourth-gen thermal sensor and a refresh rate of 60 Hz that is extremely useful when you have moving targets in your field of view.

It comes with numerous digital features that are common in high-end models, including One-Shot Zero, a Smart Rangefinder, a Ballistic Calculator, and dual video streaming and recording. The Thor 4 probably has more features than you’ll ever use, but it’s still your right to have them.

This sight boasts an extremely low power consumption rate, eliminating any worries you may have about its countless features draining its battery life. You can use the Thor 4 practically for 18 hours before you need to recharge it.

Its ballistic calculator improves accuracy and precision by calculating wind, optimal settings for several different settings, range, and all other types of useful settings. The Thor 4 384 thermal optic is an all-in-one beast of a system that leaves nothing to be desired.


The Thor 4 has some quality control issues that relate to firmware glitches. There’s also the issue of the sight powering off before hunters are actually able to use it. However, this is not a problem that ATN faces alone. Most high-end digital optics, no matter the brand, usually have electronic issues.

ATN has tried to offer hunters a good imaging performance, but the fact remains that you cannot compare a 640x480 sensor to a 384x288 sensor. The sight picture is not as sharp as other models, and you’ll see greater deterioration when you magnify with a higher power and at longer ranges.

Bottom line 

The Thor 4 is a smart and high-performing optic, but it still classifies as an entry-level digital scope. If you don’t want to burn a hole in your pocket and have a strict budget, then this unit might be your only choice.

3. Best Clip-on Thermal Sight: Armasight Apollo Pro 640 Scope

best budget reflex sight

A clip-on sight's basic idea is to attach it to your rifle whenever you need it and remove it and stash it away when you don’t. Clip-on thermal optics allow hunters to use their scope just as they would normally, but with additional thermal vision capabilities.

The FLIR Apollo Pro 640 is nothing less than the real deal. It’s jam-packed, loaded, filled to the brim with the latest technology and countless features to give you clear sight at night.


  • Does not require any zeroing
  • Easily sits in line with a daytime scope·      
  • FLIR Tau-2 uncooled microbolometer sensor produces high-quality images.
  • Water-resistant design works in all weather conditions, including smoke, rainfall, and fog·
  • 30 Hz refresh rate provides crisp and clear images of your target


  • Needs extended rail on the rifle

Our Review

The Armasight might be the most advanced clip-on sight you’ll ever see. If you prefer using the same gun for both night and day purposes, a clip-on is the product for you. High-quality clip-on units give hunters the functionality to surveil, detect, search, and hunt with the additional advantages of thermal sight without switching guns, thereby avoiding the trouble of mounting the sight and re-zeroing the scope every single time. And this is exactly what the Armasight can do.

This clip-on thermal sight easily sits in line with the daytime scope. While you can lock it down to your weapon’s rail to ensure a tight and secure mount, you can also remove it using the sight’s quick-disconnect system. It’s specifically developed to sit and operate in line with a magnified sight, but you can use it as a separate monocular as well.

The Apollo-Pro MR 640 boasts a refresh rate of 30 Hz, 640x512 thermal sensor resolution, and a 50mm objective lens. It further comes with an optical magnification of 1x, but you can scale to 8x power if you use the digital zoom. It also offers six pattern and four reticle color options, along with a wide range of imaging types that include Rainbow, Black Hot, White Hot, and more.

The model comes with a wireless remote for quick and easy operation, so you don’t have to change your armed position or lose your focus. It also offers two battery options you can choose from: 4 AA or 4 CR123A V batteries that will run for approximately 7 hours.

The sight is extremely versatile as it fits both Weaver and Picatinny rails. You can also add an external power supply or a recording device that can shoot some incredible thermal videos. Since the Armasight ranges somewhere in the mid-$3000s, it’s also affordable, particularly because of its features and specifications. Lastly, Armasight often backs its products with a three-year warranty, so you can easily use this clip-in sight in the most extreme weather conditions as well.


One major limitation of the Apollo-Pro MR 640 is that you’ll have to purchase an extended Pica tinny or weaver rail to use the sight.

Furthermore, if your day scope has a power of 3 or more, then the sight picture might be distorted. It’s also a bit difficult to line up with the day scope, and you may need to use two mounts. The quality of the adapters that come with it could also be improved.

Bottom line

FLIR masters the approach of lessening the adjustments hunters have to make on their weapons and sight systems and increasing their time out in the field. All in all, the FLIR Apollo Pro 640 is ideal for tactical operatives and predator hunters who want to have both a thermal and a daytime riflescope in their arsenal.            

4. Best for Hunting: Trijicon IR Hunter Mk 3

best reflex sight for the money

An extremely modern thermal sight, the Trijicon IR Hunter Mk 3 is perfectly suitable for hunting. The powerful thermal optic gives you a wider field of view, which is an essential upgrade to the Mk 2 series.


  • Powerful magnification range for a clearer view.
  • Reticles scale to magnification similar to an FFP scope·
  • Multi-purpose design maximizes versatility· 
  • ‘Enhanced Target Recognition’ applies gain settings across the whole spectrum


  • Reversed windage turrets
  • Bit expensive than other models

Our Review

Trijicon is famous for its high-quality and full-featured optics, and IR Hunter Mk 3 is clear proof of that. The optic features a 60hz refresh rate that offers hunters as close to real-time tracking as possible. In fact, there’s no framerate drop or slow down when you’re tracking moving targets. Resembling a normal day scope, the IR Hunter Mk 3 is perfect for hunting.

The unit fits easily and naturally on most hunting rifles and makes the change from a day scope to a thermal sight as smooth and fluid as possible. Furthermore, since it’s a thermal sight, it works in both night and day environments. It has several different features, including five reticles, a stadiametric rangefinder, and a 2.5-20 power magnification. You can also convert the sight into a clip-on optic.

The Hunter Mk 3 features a 35mm Germanium objective lens, while a highly-transmissive, replaceable IR window protects the lens. It has an optical magnification of 2.5x, but you can use the 8x E-Zoom as well if you want to get a closer look. All eight reticles in the sight are high-precision devices that scale in size when you change and adjust magnification. This makes them equal to the first focal plane (FFP) reticles found in premium riflescopes.

Moreover, the Mk 3 boasts a 640x480 display and sensor resolution, Black-Hot and White-Hot imaging, and numerous advanced features to attain focus, contrast, and target recognition. All these statistics help ensure the best thermal imaging you’ll ever see on a sight. Enhanced Target Recognition (ETR), a stadiametric rangefinder, Edge Detect, and Digital Contrast Enhancement (DCE) are features that will certainly change the way you hunt, whether it’s fugitives, coyotes, or other animals.


Unlike conventional riflescopes with a windage turret present on the right and an elevation turret present on the top, the IR Hunter Mk 3 reverses the two turrets' position. This is not exactly a limitation but may take some getting used to.

This unit does not have great battery life and is basically a battery hog. The battery life will deplete completely within 3.5 to 6 hours, but you can easily remove the sight to upload data and replace the battery thanks to the dual lever LaRue quick-detach weapon mount.

Bottom line

The IR Hunter Mk 3 from Trijicon is undoubtedly one of its best thermal sights. Detailed reticles, digital technology, and brilliant technology basically scream out expensive. Its price tag makes it not suitable for everyone, but the most superior sights worth their tenacity rarely are.

5. Best Value for Money: OPMOD Thor LT 3-6X

best budget reflex sight

The OPMOD thermal sight is an Optic Planet’s modification of the Thor LT 3-6x model by ATN. It costs less than $1200, boasts a ton of extra features, and comes with a limited lifetime warranty.


  • Comes with a free QD mount.
  • Extremely affordable and budget-friendly.
  • Ultra-lightweight design· 
  • Battery life of more than 10 hours.


  • Only Black Hot/White Hot color modes.
  • Has some software bugs·
  • Does not come with mounting rings.

Our Review

What makes a unit worth the money is mostly subjective, but it should be comparable to similar, high-quality models, high-performing, and economical. The OPMOD covers all three conditions.

The OPMOD Thor has all the popular features and functions of the ATN Thor, but with a few modifications that make this model a specialized thermal sight ideal for all types of hunters. These mods are subtle, such as the OPMOD logo on the unit’s body, but they also have much more obvious advantages, like a quick-detach mount that you need to purchase separately with the ATN model and a specially designed reticle that the ATN model doesn’t have.

This is actually a 68 MOA circle dot reticle that’s one of the best and most popular reticles due to its aiming points and fast target acquisition. With this sight, you already have multiple reticles you can use, so why not have the 68 as well?

Since this model is an ATN Thor LT 3-6x at its core, it boasts multiple thermal displays, long recognition, detection, and identification ranges, the standard One Shot Zero feature, and extremely low power consumption that allows it to last for more than 10 hours. All in all, OPMOD Thor LT 3-6X is certainly worth a look.

One of the most notable features of this optic is its compact and ultra-lightweight frame. The 1.4 lb sight also allows you to easily switch between weapons, which would normally be difficult with heavier models.


The sight picture is a bit grainy but becomes a lot clearer once you adjust the focus. That’s why it would be better if the focus was closer to the eyepiece instead of being on the other side of the scope.

The OPMOD Thor LT also does not offer an option for videos, photos, or firmware updates. However, the lighter software means that there are fewer chances of a freeze or hard reset.

Bottom line

If you don’t want to burn a hole in your pocket or are just starting out with hunting, the OPMOD Thor LT 3-6X is perfect for you. If you’re only planning on hunting down deer, or coyotes, then you’ll find its features to be up for the task.

How to Select the Right Thermal Reflex Sight

thermal reflex sight

Thermal reflex sights are not affordable or cheap optics. They boast a technology that’s newer than night vision, which explains why they’re still so high-priced. The best thermal reflex sights can detect temperature differences, and their ability to do so primarily depends on the thermal sensor/detector sensitivity. It’s also important to note how display resolution affects image quality and how the pixel quality becomes poorer as the power increases.

Some important features to keep in mind are:


The best thermal sights cost over $5000. These units are often the best that money can buy, but you’ll also get practical use from models that are in the $2000 to $5000 range. If you want a thermal sight that costs less than $1000, you won’t be able to find one. There are some units available under $2000, but make sure you’re brand-specific so that you get a money-back guarantee and good warranty coverage as quality control issues are common within this price range.


Thermal imaging sights are usually big and heavy. The average weight for a traditional thermal sight is approximately 2 pounds. Lightweight units weigh around 1-1.5 pounds, which is similar to standard daytime rifle scopes. Although thermal units have the same length as traditional rifle scopes, their internal components make them much wider. Their weight and size will affect your entire sight system and tactical or hunting weapon.

If you want a compact and lightweight option, opt for a clip-on system. Along with shedding weight and size, these models are also easily attachable and removable and allow hunters to use them with their daytime scope.

Recognition/Detection Ranges

Thermal optics offer more than 1000 yards of detection range, whether it’s day or night. However, the range at which hunters can identify and recognize their target becomes significantly shorter.

These ranges differ between models, quality, and manufacturers. Make sure you research the thermal detector sensitivity before you make your purchase. Increasing magnification power can help you quickly identify and determine a faraway target, but it can also decrease pixels, resulting in a low-quality and grainy picture. Make sure you also check the display resolution, as it affects the quality and clarity of the sight picture.

Scope durability

Although thermal imaging sights offer a lot of functions, they’re essentially fragile. While they have been recoil- and shock-tested for weapon-use, they’re still not units that you should expose to natural elements for a long time as most models are only water-resistant. Make sure you consider build quality and reliability, and a good replace/repair warranty from an established brand is essential.

60Hz vs. 30Hz

The refresh frame rate updates your sight picture and makes it look as natural as possible. Most people say that the naked eye cannot tell the difference between 60Hz and 30Hz quality. However, if you’re planning on continuously hunting/tracking moving targets or being on a moving platform, it’s better to choose a sight with the 60Hz refresh frame rate for the fastest and most natural-looking sight picture.


Rifles such as the AR-10 and AR-15 have long scope rails, and most scope manufacturers make units that easily fit this length. Thus, the length won’t be a problem if you own an AR, but we cannot say the same thing for other weapons, like traditional bolt action rifles. Such rifles usually feature short scope mounts, which means that it will be difficult to attach longer optics to them. So, make sure you consider the mounting surface length before you finalize your purchase.

Thermal Reflex Sights: Frequently Asked Questions

What is a thermal sight?

A thermal sight falls into the category of infrared imaging technologies. It features thermographic cameras that utilize infrared technology to identify sources of radiation produced by heat-producing sources.

Thermal optics use infrared radiation to create an enhanced contrast sight picture, enabling hunters to detect and track targets in poor visibility. Most units combine an aiming reticle with a small thermographic camera, allowing hunters to quickly identify things that give off a heat signature.

How do thermal sights and night vision differ?

Night vision goggles or NVGs basically detect low levels of light and amplify it. Manufacturers use the clear green color on purpose because human eyes are very sensitive to green. The goggles need at least some type of light to produce a picture and cannot use energy that’s in heat form. This creates a very significant problem if you want to use night vision on incredibly dark nights or in buildings where all the lights are off.

best reflex sight for the money

On the other hand, thermal sights provide a completely different experience and better visual capability in complete darkness, even if there’s no available light.    

What are the common applications of thermal sights?

The most common application of thermal sights is hunting, particularly coyote and hog hunting. Law enforcement, military units, and search and rescue teams also commonly use these units.

Final Verdict: What is the Best Thermal Reflex Sight?

The best thermal reflex sight for you depends on what you plan to use it for. If you’re willing to spend some money, then you can opt for the Trijicon IR Hunter Mk 3.

If you’re planning on doing some hog hunting, then the SIG Sauer Echo 3 is perfect for you, while the ATN Thor 4 Thermal Riflescope is more suitable for hunters on a strict budget.