The best clip-on thermal for the scope you already own

How a thermal clip-on works

A thermal clip-on is a thermal camera and a small display that mounts in front of your day scope's objective lens. You keep looking through your own scope's eyepiece and reticle; the scope sees the clip-on's thermal picture instead of the daylight scene. ATN describes its TICO 6 as a unit that "clips on in front of your existing scope," letting you "use your current scope's reticle and eye relief" (ATN TICO 6). AGM says its Rattler-C V2 "can be easily attached in front of day scopes to quickly convert a day optic into a thermal imaging device" (AGM Rattler-C V2).

In front, not behind: every clip-on on this page sits ahead of the day scope, as its maker describes it, so the day scope's reticle and eyepiece stay in use. At dawn you take the clip-on off and hunt with the same scope in daylight.

How each one attaches is where the details differ, and where buyers get caught out:

• ATN TICO 6: a Quick Detach Mount comes in the box; the scope mounting system that clamps to your objective is sold separately for 40, 44 and 50 mm objectives.
• AGM Rattler-C V2: an ADM Picatinny mount (1.5-inch centerline height) is included, but mounting directly to a day optic "requires a compatible Front Q-R Adapter (sold separately)," per AGM.
• Guide Orion 635: Picatinny and bell mounts are optional accessories.
• SIG SAUER Echo CV25: listed with a quick-disconnect mount.
• Pulsar Krypton 2, DNT Hydra HS225 and TKC Sirius: also work as handheld units, and the Hydra and TKC as standalone scopes.

For hog hunting, that makes a clip-on a practical middle path: one rifle, one zeroed scope, thermal when the hogs come out. The rest of the thermal and night vision hub covers dedicated scopes and handheld scanners.

What makers say about zero and day-scope magnification

Zero. This is the big clip-on question, and the makers say less than you'd hope. Of the product pages we checked, only ATN addresses it: the TICO 6 lets you use your scope's reticle "often without the need to re-zero." "Often" isn't "always." AGM, Guide, Pulsar and DNT make no zero claim on the pages we read. So treat zero as something you confirm, not something you assume: mount the clip-on, shoot a group at your hunting distance, and check it against your daylight zero before you take a shot at a hog. Our guide to zeroing a thermal scope walks through the process.

Day-scope magnification. Makers publish a recommended range. ATN lists "Optimal Day Scope Magnification: 1-8×" for the TICO 6 256. AGM says the Rattler-C V2 is "optimized for use with LPVO and traditional magnified optics (ideally 1x to 6x magnification)." The optics explain why: your day scope enlarges the clip-on's picture, but it can't add thermal pixels. The detail on the hog is set by the clip-on's own sensor and lens, and turning the day scope up past the recommended range just makes those pixels bigger.

Clip-on or dedicated thermal scope?

A clip-on makes sense when:

• You already own a good day scope with a reticle and zero you trust.
• You hunt the same rifle by day and by night and don't want to swap optics and re-zero.
• You want the thermal to double as a handheld scanner (the TICO 6, Krypton 2, Orion, Hydra and TKC all list a handheld mode).

A dedicated thermal scope makes sense when you don't have a suitable day scope, when you want one sealed unit with built-in zero profiles, or when weight and length on the front of the rifle matter. In the same budget tiers, several scopes add built-in rangefinders, such as the ATN ThOR 6 Elite and oneleaf Mars; among these clip-ons, only the TKC Sirius lists one. Compare them on our best thermal scope for hog hunting and best thermal scope under $2,000. If you're still deciding whether to start with a handheld instead, read thermal monocular vs thermal scope.

How we picked

We started from the thermal clip-ons Amazon listed when we checked on September 19, 2026, and read each maker's product page (for the SIG SAUER Echo CV25, a retailer's spec page, because SIG's site blocked automated access). Clip-ons are scored on our published thermal rubric: sensor and lens for identifying a hog (30%), usability at night (20%), battery and power (15%), durability (15%), warranty and support (10%) and value within the budget tier (10%). Detection ranges are the maker's claims.

We haven't tested these units; scores come from published specs and the rubric on our How We Choose page. The list holds seven because that's every thermal clip-on in our Amazon-verified registry.

Pixels on a hog through a clip-on

Because the day scope can't add pixels, the clip-on's own pitch and lens set the detail. The math: inches per pixel = distance (yd) × 0.036 × pitch (µm) ÷ lens (mm); pixels across the hog = its length ÷ inches per pixel. We use a 60-inch hog, the top of the Missouri Department of Conservation's size range for feral hogs ("length: to 5 feet," MDC). This is illustrative math, not a test.

Pulsar doesn't publish the Krypton 2's lens focal length or pixel pitch, and the TKC Sirius listing gives no pitch, so neither is in the table. Two things stand out. The Orion 635's 35 mm lens puts the most pixels on a hog of the clip-ons we can work out. And the Echo CV25 and TICO 6 put the same pixels on the animal, but the Echo's 640 sensor shows a view about two and a half times as wide, which helps you follow a sounder through your day scope.

The picks side by side

The picks in context

1. Guide Orion 635

The best hog-ID sensor here and the best value (8.3). Guide lists a 640x512 VOx sensor with 12 µm pixels and 15 mK NETD behind a fast 35 mm F0.9 lens, a 0.49 in 1920x1080 AMOLED, IP67, a 6,000 J rating and a 10-year warranty on the thermal sensor, all in about 10 oz, the lightest unit here. The trade-offs: Guide's product page lists no photo or video recording or Wi-Fi, runtime is up to 6.5 to 7 hours per 18500 (two included; the page gives both figures), and the Picatinny and bell mounts are optional accessories. It sat in the $1,000 to $2,000 tier when we checked.

2. SIG SAUER Echo CV25

A 5-inch, 640x512 clip-on with 20 mK sensitivity, a 25 mm lens and a wide 17° view, a removable 18650 rated up to 9 hours, photo and video with audio, and setup and live streaming through SIG's BDX app. Its warranty is SIG's Infinite Guarantee, an unlimited lifetime term, the strongest here. It loses points only on value: it sat in the top budget tier, where the Orion gives you a 640 sensor with a longer lens a tier lower.

3. Pulsar Krypton 2 XQ35

A premium 384x288 front attachment with <25 mK NETD, a 1920x1080 AMOLED display, up to 11 hours per charge on the IPS7 pack, IPX7 and a recoil rating up to .375 H&H. Pulsar calls it a clip-on/monocular hybrid, and it works with a Bluetooth remote. Pulsar's page doesn't list the lens focal length or pixel pitch, and it sits in the top budget tier with a 384 sensor, so it scores low on value. Warranty: three years, five with registration.

4. ATN TICO 6 256

Our pick under $1,000. A 256x192, 12 µm, ≤20 mK sensor behind a 25 mm F1.0 lens, with 64 GB, Recoil Activated Video, a wireless remote, IP67, a 6,000 J rating, a -22°F to 131°F operating range and a five-year warranty. ATN is the only maker here whose page speaks to zero ("often without the need to re-zero") and lists a 1x to 8x day-scope range. The removable eyepiece turns it into a monocular. Limits: about 4 hours per 18650 (two included), an 800x600 display, and the scope mounting system costs extra.

5. DNT Optics Hydra HS225

A 3-in-1 unit: standalone scope, clip-on or handheld. DNT lists a 256x192, 12 µm, ≤25 mK sensor behind a 25 mm lens, a 1024x768 micro-OLED, 32 GB, IP67 and a .50 BMG recoil rating in 13.1 oz. DNT also says its Super Resolution processing makes a 256 image look like a typical 384; that's the maker's claim. Runtime is up to 5.5 hours per 18650, the warranty is two years, and DNT lists a 3x base magnification, narrow for close scanning.

6. AGM Rattler-C V2 19-256

The runtime leader: up to 11.5 hours per NE-4400 battery with two in the box, plus a 1024x768 OLED, IP67, 16 GB and Wi-Fi. The 19 mm lens and <35 mK NETD trail the 25 mm clip-ons, AGM's product page doesn't list the warranty terms, and the Front Q-R adapter for direct scope mounting costs extra. AGM recommends day optics of ideally 1x to 6x.

7. TKC Sirius 256x192

A 3-in-1 (clip-on, scope or handheld) with a built-in laser rangefinder and a listed ≤18 mK sensor behind a 25 mm lens. Every spec we have comes from the Amazon listing title; we found no maker spec page with battery, IP rating or warranty terms, so it scores last. Buy it only if the rangefinder at this budget outweighs the missing documentation for you.

What to look for in a clip-on thermal

1. Fit for your day scope, first. Know your scope's objective diameter and check the maker's adapter list before you buy. ATN sells mounting systems for 40, 44 and 50 mm objectives; AGM's scope adapter is extra.
2. A day scope inside the maker's magnification range. ATN lists 1-8x for the TICO 6 256; AGM says ideally 1x to 6x for the Rattler-C V2. A high-power hunting scope may be outside both.
3. The clip-on's own sensor and lens. They set the detail on the hog; your scope only enlarges it. A 640 behind 35 mm (Orion) leads this group.
4. A zero plan. Only ATN makes a zero statement, and it says "often." Budget ammunition and daylight to confirm point of impact with the clip-on mounted.
5. Weight on the front of the rifle. The picks run from about 10 oz (Orion) to 18.8 oz (Echo CV25), in front of whatever your scope already weighs.
6. Battery and recording. Ratings run from about 4 hours per cell (TICO 6) to 11.5 (Rattler-C). The Orion lists no recording; the TICO 6 has Recoil Activated Video.
7. Warranty. SIG's unlimited lifetime Infinite Guarantee, Guide's 10 years on the thermal sensor, ATN's five years, Pulsar's three (five with registration), DNT's two. AGM's page doesn't list terms.

What each budget tier buys in a clip-on

Clip-ons sit in the same budget tiers as dedicated scopes with similar sensors, and sometimes a tier higher. You're paying to keep your day scope in the loop. For a tier-by-tier view of thermal prices, see how much a thermal scope costs, and for sensor sizes, 256 vs 384 vs 640 thermal.

Setting up a clip-on for a night hunt

1. Mount it in daylight. Fit the adapter to your objective and tighten it to the maker's instructions while you can see what you're doing.
2. Set the day scope inside the maker's range. Low power first; you can always add a little.
3. Check point of impact. Shoot a group with the clip-on mounted at the distance you'll hunt, and compare it with your daylight zero.
4. Mark the mount. A paint pen line on the adapter and clip-on shows at a glance whether anything has shifted since you checked.
5. Carry the spare battery. The makers rate these from about 4 hours per cell (TICO 6) to 11.5 (Rattler-C); anything short of a full night needs the spare, charged.

Clip-on mistakes

• Assuming it holds zero. Confirm point of impact with the clip-on mounted, at your hunting distance.
• Forgetting the adapter. Several makers sell the scope clamp or adapter separately.
• Cranking the day scope to full power. It magnifies pixels, not detail. Stay inside the maker's recommended range.
• Buying on the day scope's quality. A premium day scope won't improve a 256 clip-on's image.
• Ignoring the added length and weight. A clip-on hangs in front of your scope; check that the rifle still balances on your rest. Our shooting sticks and tripods page helps there.
• Treating one rifle as the whole plan. Shooting removes a few hogs at a time; our guide on how to get rid of feral hogs covers trapping whole sounders.