July 2026 - Written by the HeatSight Optics Team
HeatSight TPM O3 25LRF Review - The TPM O3 25LRF is the least expensive laser-rangefinding thermal we sell - $599 - and it isn't a stripped-down toy: a ≤30 mK 384 sensor, a 1,500-meter rangefinder, and a big 2.69-inch display in a one-pound package. It's the entry ticket to ranging-equipped thermal, full stop.
The O-series is our compact LRF platform: a 25 mm objective, a one-pound (500 g) body, and - unusually in this class - a big 2.69-inch 800×600 OLED display rather than a small eyepiece screen. Housing is IP66, impact-rated to 1000G, running -20°C to +60°C on a single 18650 (3,500 mAh) for 5+ hours.
The 384×288 core runs a ≤30 mK NETD - tighter than the ≤40 mK typical of this price class - on the standard 12 μm pitch. The 2.69" display changes how the unit is used: it's glanceable, shareable, and far easier on the eyes across a long night than pressing your face to an ocular.
Full 1,500-meter ranging with ±1 m near-field accuracy, on a unit this size and price. Zoom steps at 1×/2×/4×. Six palettes, PiP, hotspot tracking, four menu languages, 16 GB recording, USB-C charge and export.
The O3 lives in my coat pocket through the cold months. Scanning sessions run long because the wide view makes them easy, ranging checks against known distances come back consistent, and the cold has not yet gotten it to misbehave; batteries drain faster in the teens like they do in everything, so spares ride in the inside pocket where they stay warm. A ranging monocular at this price is the cheapest way to know how far away anything is at night.
1,500 m LRF in a one-pound package: The most portable ranging thermal we make.
30 mK NETD: Better thermal sensitivity than most competitors at the price.
$599: The lowest-cost path to a rangefinding thermal optic that we're aware of, anywhere.
Common 18650 power: One cheap, ubiquitous cell; 5+ hour runtime.
For close-cover hunting, property checks, and first-thermal buyers who want the LRF without flagship spend, the O3 is the answer. Want the same package with double the sensor? That's the O6 for $300 more. 2-Year Limited Warranty.
Specifications: 384×288 VOx, 12μm, NETD ≤30mK | 25mm, 10.5°×7.9° | LRF 10-1,500m | OLED 800×600, 2.69" | ≤50Hz | 6 palettes, PiP, hot tracking | 16GB, JPG/MP4, USB | 18650 3,500mAh, ≥5h | -20°C~+60°C | 1000G | IP66 | 196.5×96×66mm | 500g
The HeatSight Optics TPM O3 25LRF is available at heatsightoptics.com for $599 (regularly $999). It's in stock and ships from our Michigan facility. Questions about which HeatSight scope fits your hunting or property-security setup? Call us at (313) 338-8168 - you'll talk to the people who actually build and flash these units, not a call center.
This review was written by the HeatSight Optics team based on our own design, bench, and field testing of production units. We build these scopes, so consider the source - and consider that we also publish the cons, because we'd rather you buy the right scope than return the wrong one.