Thermal imaging fills a fundamentally different niche than analog image-intensified night vision. Where a traditional NVG amplifies ambient photons, a thermal sensor reads heat signatures — meaning it works in total darkness, through smoke, and in conditions where even the best Gen 3 tube struggles. Thermal does not replace night vision; it complements it. Understanding what thermal devices are available — and what role each fills — is the first step toward integrating this capability into a layered coherent loadout.
The thermal devices stocked and sold through T.REX Arms span four categories of use: handheld scanning and spotting, helmet-mounted observation, clip-on augmentation of existing day optics, and dedicated thermal weapon sights. Several of these devices bridge multiple roles, reflecting the trend toward multifunction thermal platforms that justify their significant cost by eliminating the need for separate units.
Handheld and Helmet-Mounted Thermal Monoculars
N-Vision NOX18
The N-Vision NOX18 is a compact thermal monocular built around a 12-micron BAE thermal core running at 640×480 resolution and a 60 Hz refresh rate. Its 18mm F1.0 lens provides a 24.3° × 18.3° field of view, with digital zoom scaling up to 8×. Three polarity settings — white hot, black hot, and edge detect — let the user optimize the display for the task at hand, whether that is scanning tree lines or identifying personnel in an urban environment.
What makes the NOX18 particularly useful in a night-fighting loadout is its modularity. It can be configured for left or right eye use and paired with another NOX or a PVS-14 on a dual bridge mount. This fusion setup — one eye on image-intensified night vision, the other on thermal — gives the operator the spatial awareness of an I² tube alongside the detection advantage of thermal. The unit is nitrogen-purged to prevent internal fogging and built in the USA. It is ITAR-restricted.
Eight user-selectable reticles are included, allowing the NOX18 to serve double duty as a rudimentary weapon sight when helmet-mounted shooting is not practical and a clip-on is not available, though it is primarily designed as a scanning and spotting tool.
Trijicon OASYS SkeetIRx
The Trijicon OASYS SkeetIRx occupies the ultra-compact end of the thermal spectrum. At 8.6 oz and measuring just 4.0” × 2.4” × 1.7”, it is one of the lightest capable thermal packages available. It uses a 640×480 sensor with a 17-micron pixel pitch and offers 1× magnification with 0.5× and 2× digital zoom.
The SkeetIRx is designed for users who need thermal detection in the smallest, lightest possible form factor — think of it as a thermal analogue to the PVS-14 in terms of philosophy: simple, proven, and easy to integrate into a helmet setup without creating a front-heavy, neck-straining platform. At $15,000, it represents the premium end of micro-thermal technology, and its value proposition rests on weight savings and optical quality rather than feature density. Like all thermal devices in this category, it is ITAR-restricted and ships only within the United States.
Multifunction Thermal: Weapon Sight, Helmet Unit, and Clip-On
iRayUSA RICO MICRO RH25 V2
The iRayUSA RICO MICRO RH25 V2 is arguably the most versatile single thermal device in the current lineup. It is designed to function in three distinct roles: as a helmet-mounted observation monocular, as a clip-on unit that sits in front of a standard day optic, and as a standalone thermal weapon sight with onboard reticle options.
The sensor is a 640×480, 12-micron InfiRay MICRO II core running at 60 Hz with thermal sensitivity under 15 mK — sensitive enough to detect subtle heat differentials at extended range. Detection range is rated at 1,375 yards. The AMOLED display outputs at 1440×1080 resolution with seven reticle patterns and four color palettes: White Hot, Black Hot, Red Hot, and Color. The magnesium alloy body is IP67 rated and tested to a 1,000 g/s² recoil rating, clearing it for use on calibers up to .300 Win Mag.
The key enabler for the RH25’s multifunction role is the iRay Pictail Shoe and ADM MQD mount system, which allows rapid swapping between helmet and Picatinny platforms. This means a single device can serve as a scanning tool during movement, then transition to a clip-on or standalone weapon sight when the situation demands precision engagement. Onboard features include 64 GB of internal storage for recording, WiFi connectivity, Bluetooth remote control, and USB-C for data transfer and external power. Runtime exceeds 6.5 hours on the included 18650 battery.
For those building a thermal capability on a budget (relative to the thermal world), the RH25 V2’s ability to cover three roles with one purchase is compelling. Understanding how clip-on thermals integrate with existing day optics is covered in Clip-On Thermal for Existing Optics.
Dedicated Thermal Weapon Sight
Trijicon REAP-IR 35mm
The Trijicon REAP-IR 35mm is a purpose-built thermal riflescope — not a monocular that doubles as a weapon sight, but a dedicated optic designed for precision shooting through thermal. It uses a 640×480, 12-micron vanadium oxide sensor housed in a 7075-T6 aluminum body. The 35mm objective lens provides greater magnification and detection range than the compact monoculars above, at the cost of weight (28.18 oz) and form factor.
The integrated DVR records 640×480 MP4 video directly to an SD card — useful for after-action review, documentation, and training analysis. A USB-C port supports both external power (extending the roughly 4-hour runtime on two CR123 batteries) and video output. The REAP-IR is a serious tool for applications like property security, hunting in low-light conditions, and defensive overwatch where a dedicated thermal sight on a rifle provides capability that a handheld or helmet-mounted unit cannot match.
The REAP-IR sits on a standard Picatinny rail and replaces the day optic entirely. This is a different integration philosophy from the clip-on approach of the RH25 V2 or the traditional NVG-enabled rifle setup that pairs a PVS-14 with an IR laser. Both approaches have merit; the right choice depends on whether the user needs to engage targets through thermal or simply detect them before transitioning to another aiming solution.
Selecting a Thermal Device
The hierarchy of thermal acquisition generally follows a predictable pattern:
- Handheld scanner first. A thermal monocular like the NOX18 provides detection capability — finding people, animals, or heat sources — without requiring a weapon-mounted commitment. This is the highest-value first purchase for most civilians.
- Clip-on or multifunction unit second. The RH25 V2’s ability to serve as both a helmet device and a clip-on makes it a strong second acquisition, bridging observation and engagement.
- Dedicated weapon sight third. The REAP-IR is a specialist tool for users who have already solved their observation problem and need precision thermal engagement capability.
All thermal devices sold by T.REX Arms are ITAR-restricted and ship only within the United States. The legal landscape around thermal ownership is covered in Thermal in the Civilian Context: Use Cases and Legality.
Understanding how thermal fits alongside analog night vision — and why running both simultaneously is the gold standard — is essential. For a deeper look at the underlying technology, see How Thermal Imaging Works: LWIR Sensors and Microbolometers. For guidance on physically mounting and configuring these devices within a helmet ecosystem, refer to Bridge Mounts and Dual-Tube Configurations.