TFB Review: Infiray FAST FAL19 – Red Dot Thermal Fusion Sight

Eric B
by Eric B
Review of the Infiray FAST FAL19 – Red Dot Thermal Fusion Sight

This is a review of the Infiray Fast FAL19 34mm Red-Dot Thermal Fusion Scope. TFB were among the first to get a sample to try out this brand-new product and technology, and we had a lot of fun doing so. The FAL19 sight offers a combination between an EOTech-style reticle and a thermal overlay, for a thermal fusion effect. If you don’t need the thermal (and want to save batteries), there is a simple red or green dot only also.

Infiray @ TFB:

During my testing, I let a lot of people try the sight, and everyone that looked through the Infiray FAST FAL19 said “WOW” or laughed in amazement at how cool this device is, with the thermal fusion. Just check the images below and see for yourself. At the same time, it looks a bit misplaced on a rifle or carbine.

The thermal performance was better than I expected. The FAST FAL19 uses a 19 mm thermal objective lens, with a 12µm 384×288 thermal sensor. The NETD is claimed to be ≤40mK. The lens sits at the bottom of the sight, as close to the bore as possible, and whatever information the thermal sensor collects is projected as a “see-through” onto the window where you also have the reticle.

Below: There’s no hiding. If there is heat, this sight will detect it. Since the thermal image is an on-screen overlay, you can also see the red rear lights of the car and other details in color. This is a low light condition, but not pitch black. A man is walking to the left, there’s a Volvo SUV with ignition and lights on to the right. There are a few cars to the left as well, semi-outside the thermal window.

You can define green-hot or black-hot overlay in various modes like full thermal, highlight and outline. Zeroing the sight is easy. We zeroed the carbine and had a blast at the range, trying out the Norwegian A-TEC Submachine Gun suppressor with tri-lug attachment at the same time. The sight works really well between 15 to 50 meters, which was the furthest we shot due to the limitations of the shooting range. There were no issues with thermal reflections from the firearm or the suppressors in this configuration.

The sample images from Infiray below give you an idea of what kind of images the thermal can produce. On top of this, you get a reticle. The display is OLED.

The Infiray riding a B&T APC9 carbine. A pretty good marriage. The A-TEC PMM-6 Glock Pistol Suppressor was reviewed recently.

Basic overview

The Infiray Fast FAL19 has a black aluminum body and resembles an EOTech sight – except it has a thermal sensor. The attachment is via a screw-on Picatinny mount, with a recoil lug. The window is large at 34mm×25mm and has a pretty strong purple-violet tint. I don’t have the means to measure it, but it doesn’t feel like there’s a huge loss of light transmission through the screens, which includes a heads-up/on-screen display.

Below: Here is what the Infiray FAST FAL19 looks like out of the box. The Picatinny could be used for other attachments, like a rangefinder.

Below you see the battery compartment. The unit uses two CR123A batteries or USB-C for external power. The battery life is claimed to be around 4 hours, using thermal. Red dot mode is said to offer 65 hours. There is also a video out cable. The Left-Up and Down screws are for zeroing the red dot only.

As you can see, there’s a recoil lug to keep the sight in place. I understand the mount is spring-loaded, to avoid recoil shock going into the sensitive thermal sensor. The dimensions of the sight are 175×62×86 mm and the weight is 590 grams (1.3 pounds).

A guide to what does what, from Infiray.

Images taken through the Infiray FAST FAL19.

Important note about these images. The device does not have any internal photo or video recorder, so everything you see here is taken with an iPhone 12 Pro. While it produces excellent images, it is always difficult for any camera to do well in dusk and darkness and difficult conditions where you have a bright display and almost full darkness around. You really have to see the unit yourself to realize its full potential, so these images are merely samples of what to expect.

Below: Chimneys at about 1250 meters. Houses and trees from about 30 meters and further. In these images the sight is not attached to any firearm, it’s just on a tripod.

And black hot.

Below: This image is interesting. The middle house is about 160 meters away. Note the lamp, bottom right, and you realize this is a fusion image, as thermal doesn’t see the light from street lights like this. So part of the image is actually non-thermal. You also see two lights on the building to the left. Thermal Fusion!

Below: An image that shows the ambient light for the image above. Again, it’s really difficult to take steady images during these conditions.

More thermal fusion. The thermal image doesn’t cover the full size of the screen.

Below: And zoomed out version.

The thermal has a short delay, or latency, if you move the sight fast but should work for most cases.

Below: An Audi Avant at about 100 meters. The car just parked, so the engine and the brakes are still hot.

Below: A 6×6 in front of a house. Autumn time, nothing is really “hot” here apart from the chimney, some vents and the uninsulated windows of the house. Did you spot the flat tire?

The Infiray FAST FAL19 in a home defense or CQB situation.

Important note: the sight is just attached to a tripod in these images.

Here is a simulated situation. The corridor has only minimal lighting, you hear sounds from the room in front of you but you can’t see anything. In the image below, you’re in that corridor looking into the even darker room. The silver is the tripod head and the green is from the screen of the FAL19. The distance to the door is about 2-3 meters. You see nothing!

When you look into the FAST FAL this is what you see, in outline mode. So there appears to be a human in there, and there seems to be some kind of firearm involved as well. This is a still image, in reality, it isn’t blurry like this, and in outline mode, your brain will help you put the puzzle together.

Outline mode is the coolest of them all, but probably the least useful in situations like this. Sometimes it looks like a cartoon, that is drawn live in front of you.

So let’s see about that suspect, is he or she armed or not?

Oh yes, in other modes we see certain things more clearly.

Looks like a Browning BAR! Note the pistol grip.

Over to mother nature, outside in the wild

Below: This is some kind of red deer (most likely a roe deer since it’s alone, but it could be a fallow deer since they’re pretty common in this place) at about 150 meters. The deer is a few meters into the bushes, and the photo is taken with an iPhone with a loss of image quality. But you get the idea. It’s not a shot I’d take unless I’m in an emergency, but the thermal fusion is great for discovering warm objects you wouldn’t see otherwise.

Below: Here you can see the menu, where you can change a lot of settings. Note the red dot here.

The lens has rubber protection, but without it, it’s fairly unprotected on the firearm.

Below: Like I said, the FAST FAL19 is a great tool, but it sits rather high on the gun and looks odd.

B&T APC9 and Glock with A-TEC suppressors (from Norway).

You can shoot like this until the suppressor heats up…

A Blaser R8 Carbon and the FAST FAL besides to scout for animals.

Here’s a good example, even if there is strong light coming on to you (from a flashlight or weapon light, for instance), you can still see through. The sight is just attached to a tripod here.


The price in the USA is $4,399 and it will be released during SHOT Show 2023. If you’re at the exhibition, take the opportunity to experience it yourself. The product is Made In China.


Daytime and nighttime optics are merging in all sorts of fashion, and the Infiray FAST FAL19 Thermal Fusion Sight is an excellent example of what can be done today. Is it perfect? No, but I still loved using it and like I mentioned in the beginning, we had lots of positive laughs using it and exploring the performance. It’s difficult for the brain to comprehend at first. This is a niche product that will attract a certain crowd.

Let’s imagine for a while that I lived in a country where I was allowed to keep a firearm by my bed for home protection (unfortunately I don’t). Would I consider using the FAST FAL19? Yes, it has its benefits in some situations but there’s also a multitude of other options. Perhaps turning on a thermal isn’t what I’d do first to defend myself. However, if I was given a heads-up, and a few minutes to prepare myself, I’d do it. One positive is that the thermal is passive. Apart from the light from the display, there’s nothing else emitting. The thermal can also see things that night vision won’t. The negative side is the battery life, even for the red dot only.

Could it be used for hunting? Yes, probably best for close-range wild boar hunting and there are several videos on YouTube if you search.

Airsoft? For sure, this would be a great application. Don’t underestimate how much money some gamers are ready to spend, and they will have quite an experience with this sight. I’m pretty sure their hit percentage would increase quite a lot using this technology.

You can find Infiray’s Red-Dot Thermal Fusion Scopes here:

Eric B
Eric B

Ex-Arctic Ranger. Competitive practical shooter and hunter with a European focus. Always ready to increase my collection of modern semi-automatics, optics, thermals and suppressors. TCCC Certified. Occasionaly seen in a 6x6 Bug Out Vehicle, always with a big smile.

More by Eric B

Join the conversation
6 of 17 comments
  • Anomanom Anomanom on Jan 04, 2023

    The price is ouch, and I think the mount could stand a rework. But with that said, this is pretty slick piece of kit. You could put a power bank in a stock pouch and run all night with a usb cable.

    • See 3 previous
    • MikeSmith13807 MikeSmith13807 on Jan 07, 2023

      @XM1A2A Now I must know more! You're telling me there's some technicality keeping cool stuff unobtainium????!!!!

  • TDog TDog on Jan 05, 2023

    Looks cool, similar to the Steiner thermal red dot TFB reviewed a while back. But at roughly $4000, it's still a bit more than I'd like to spend.