COTI vs Fusion Goggles: Which Way to Add Thermal to Night Vision

There are two ways to get heat and night vision in the same view. You can clip a thermal onto the night vision you already own, or you can buy a goggle with the thermal built in from the start. Both get called "fusion", both put warm targets on top of the tube picture, and both cost real money. This guide compares them side by side: cost, what you see, fit, power, weight and who each one suits.

What is the difference between a COTI and a fusion goggle?

A COTI, or clip on thermal imager, is a separate thermal unit that clamps onto the objective lens of a 1x night vision tube and projects its heat picture optically into that tube. Take it off and your goggle is a plain night vision goggle again. Move it to another goggle and that goggle gets the heat.

A fusion goggle has the thermal sensor built into the housing. On our ELF-FB20, a dual tube Gen 2+ binocular, a 640 x 512, 12 micron thermal sensor sits between the two pods. Its image is shown on a 1280 x 1024 OLED and blended into the view through the eyepieces with under 30 ms of delay. Nothing clips on, nothing to line up, one battery pack. The idea behind both is the same; we explain it in what thermal fusion is.

How do a COTI and a fusion goggle compare side by side?

The thermal sensor class is the same on both. The differences are in what you already own, how the heat reaches your eye, and how much you spend.

Which costs less: a COTI or fusion goggles?

If you own a 1x analog goggle already, the clip on wins on cost by a wide margin: $2,949 against $8,299.95 and up. If you own nothing, the gap closes, because a clip on needs a goggle under it. Here are the three routes we sell, priced the same day:

The kit prices include the saving we take off in the cart: $150 off the Jerry-C Pro with any PVS-14 PRO or STANDARD, $200 off with any PVS-31 PRO. The goggles on their own are our PVS-14, from $1,784.95, and our PVS-31 PRO, from $3,799.95. The fusion binocular is the ELF-FB20 fusion binocular, from $8,299.95.

What do you see through each one?

With a clip on, the heat is projected optically into the tube, so it sits inside the same picture as the night vision, in the eye behind that tube. On a dual tube with one clip on, both eyes see the night vision and one eye sees the heat too. With a built in fusion goggle, the thermal image comes from an OLED and is blended into the view through the eyepieces.

Both give you the two main ways of showing heat: Highlight, where a warm target is filled in, and Outline, where only its edges are drawn so the tube detail around it stays clear. The Jerry-C Pro adds Breathing, a pulse that fades the overlay on and off at a speed you set. The ELF-FB20 adds a night vision only setting that switches the thermal layer off for the longest runtime. What each mode looks like in real use is in COTI modes explained.

When is a COTI the better choice?

• You already own a 1x analog goggle. A clip on adds heat for a fraction of the cost of a new fusion goggle, and you keep the goggle you know.
• You own more than one goggle. One clip on can move between them, as long as the clamp ring fits each housing.
• You want the heat only some of the time. Take the clip on off and your goggle is lighter and simpler for nights you do not need thermal.
• You want to spread the cost. Buy the goggle now, add the clip on later. Nothing about the goggle has to change.

The mounting details for each goggle are in COTI for PVS-14 and COTI on a PVS-31 or dual tube.

When is a fusion goggle the better choice?

• You are starting from nothing and know you want thermal. One goggle, one battery pack, nothing to clamp on.
• You want one power source. The ELF-FB20 runs on one battery pack, up to 80 hours with the thermal off.
• You do not want anything hanging off the front. The thermal is inside the housing, between the pods.

The trade off is price and flexibility. A fusion goggle costs more up front, and the thermal cannot move to another device. It is also built to order: the ELF-FB20 ships about 5 to 7 weeks after you order.

Is a clip on thermal a lesser kind of fusion?

No, it is a different way of getting to the same view. The thermal sensor class on the Jerry-C Pro and on the ELF-FB20 is the same: 640 x 512 at 12 micron. What changes is the path the heat takes to your eye. The clip on projects it optically into the front of one tube, so the tube carries it to you along with everything else it sees. The built in goggle shows it on an OLED and blends it in at the eyepieces. Each design has its limits. The clip on overlay lines up best past about 30 m and is not meant for use under 10 m. The built in goggle cannot lend its thermal to another device. Judge them on what you own and how you work at night, not on which one sounds more advanced.

What about digital fusion?

There is a third route people find when they search "fusion night vision": pairing a digital night vision monocular with a thermal monocular on a bridge. Our HEAT and VIPER bridge kit is that kind of setup. It puts a digital picture in one eye and a thermal picture in the other, rather than heat laid over an analog tube image. It costs far less and does a different job; we explain it in the HEAT and VIPER bridge kit, explained. If you want heat on top of an analog Gen 2+ tube picture, the choice is the clip on or the built in fusion goggle compared above.

So which should you buy?

Own an analog goggle: buy the clip on. Own nothing, want thermal from day one and want night vision in both eyes: price the PVS-31 PRO kit against the ELF-FB20 and decide whether moving the thermal between goggles, or one battery pack and nothing on the front, matters more to you. Own nothing and want the lowest total: the PVS-14 kit. The full price picture for clip on thermals is in what a clip on thermal imager really costs.

Frequently asked questions

What is a COTI?

A COTI is a clip on thermal imager. It clamps onto the objective lens of a 1x analog night vision tube and projects a heat picture into it, turning the goggle you own into a fusion view. Our Jerry-C Pro is a 640 x 512 thermal at 1x and costs $2,949.

COTI vs fusion goggles: which is better?

If you own a 1x analog goggle, a COTI adds the same 640 x 512 class of thermal for $2,949 instead of buying a new goggle. A built in fusion binocular, from $8,299.95 with us, suits buyers starting from nothing who want one device, one battery pack and nothing on the front.

How much is a COTI?

Our Jerry-C Pro is $2,949, and less in a kit: $150 off with any of our PVS-14 monoculars, $200 off with any PVS-31 PRO. The US dealer listings we compared for the same 640 x 512 class ran $3,577 to $4,475 (read 22 October 2026).

What is the most affordable COTI?

The lowest priced complete 640 x 512 clip on thermal we found was our Jerry-C Pro at $2,949, against US dealer listings of $3,577 to $4,475 read on 22 October 2026. It is also the lowest cost way we sell to add thermal to analog night vision you already own.

What is the best COTI for the money?

For an owner of analog night vision, the best value is a 640 x 512 clip on at 1x with no calibration and everything in the box. The Jerry-C Pro does that at $2,949, far below a new fusion goggle. Warranty is 3 months, up to 12 months with Operator Care.

What is the best COTI for the price?

At $2,949 the Jerry-C Pro gives you the same 640 x 512, 12 micron thermal class as our $8,299.95 fusion binocular, laid over the tube you already own, with Highlight, Outline and Breathing modes, a compass heading, a remote and a battery pack in the box.