The Guide USA Thermal Monocular TE 421 is a compact handheld thermal imaging device built for hunters, security professionals, and outdoor enthusiasts who need reliable target detection in low-light and no-light conditions. This lightweight thermal monocular delivers a 1400-yard detection range from a 400×300 uncooled infrared sensor, making it practical for extended glassing sessions without the bulk of full-size thermal gear.
What sets the TE 421 apart is the balance of portability and usability. At just 11 ounces, it fits in a jacket pocket, yet the 0.32-inch AMOLED display renders a crisp 800×600 full-color thermal image—critical when you're scanning terrain or identifying game at distance. The 25mm F1.0 objective lens and 1.9x to 7.6x magnification range give you both situational awareness and the zoom needed to confirm what you're looking at. A 25mK thermal sensitivity (NETD) means the TE 421 resolves temperature differences sharply, helping you separate warm targets from their surroundings. Manual focus lets you dial in clarity for your specific distance and conditions.
Battery life is honest: five hours of continuous operation from the built-in battery, with 20W quick charging for field top-ups. The device records both photo and video with embedded audio, stores captures on 16GB of onboard memory, and connects via Wi-Fi and Bluetooth for wireless image transfer or remote control pairing. IP67 sealing handles dust and water immersion, and the operating range of -4°F to 122°F covers most hunting and field conditions.
Key Features
- 400×300 thermal sensor with 25mK NETD for crisp target definition
- 1400-yard detection range suitable for long-range scanning and hunting
- 1.9x to 7.6x magnification with 25mm F1.0 objective lens
- AMOLED 800×600 display with six color palettes (White Hot, Black Hot, Red Hot, Green Hot, Iron Red, Blue Hot, Sepia) for visibility in varying light
- Photo and video recording with audio to 16GB internal memory
- Five-hour battery life; 20W fast charging support
- Wi-Fi and Bluetooth for wireless connectivity and remote operation
- IP67 waterproof/dustproof construction; -4°F to 122°F operating temperature
- Weighs 11.11 ounces; compact 1.85×1.85×6.10-inch form factor
Specifications
| Thermal Sensor | Uncooled VOx infrared detector, 400×300 @ 12µm |
| Thermal Sensitivity (NETD) | 25mK |
| Frame Rate | 50Hz |
| Detection Range | 1400 yards (1300 meters) |
| Objective Lens | 25mm, F1.0 |
| Field of View | 11° × 8.2° (19m × 14m @ 100m) |
| Magnification | 1.9x to 7.6x |
| Focus | Manual |
| Display | 0.32-inch AMOLED, 800×600 resolution |
| Color Palettes | White Hot, Black Hot, Red Hot, Green Hot, Iron Red, Blue Hot, Sepia |
| Eye Relief | 25mm |
| Diopter Adjustment | -5 to +5 |
| Recording | Photo, video, and audio |
| Memory | 16GB |
| Wireless | Wi-Fi (2.4G/5G), Bluetooth |
| Battery | Built-in lithium-ion |
| Operating Time | 5 hours continuous |
| Charging | USB Type-C, 20W fast charge |
| Operating Temperature | -4°F to 122°F (-20°C to 50°C) |
| Waterproofing | IP67 |
| Weight | 11.11 ounces (295 grams) |
| Dimensions | 1.85×1.85×6.10 inches (47×47×155mm) |
Frequently Asked Questions
What's included in the box?
The TE 421 ships with a lens cover, eye mask, wrist strap, 20W quick charging adapter, USB Type-C cable, quick-start guide, safety information, user manual, and warranty card. An optional Bluetooth remote control is available separately for wireless operation.
How long does the battery last, and how fast does it charge?
The built-in battery provides five hours of continuous runtime. Using the included 20W fast charger via USB Type-C, you can top up the battery significantly faster than standard charging—useful for field use when you need quick turnarounds between sessions.
Can I record video and audio with the TE 421?
Yes. The monocular records both photo and video with embedded audio to its 16GB internal memory. Files can be transferred wirelessly over Wi-Fi or Bluetooth, or directly via the USB Type-C port.
What color modes does the thermal display offer?
The AMOLED screen supports six color palettes: White Hot, Black Hot, Red Hot, Green Hot, Iron Red, Blue Hot, and Sepia. Different palettes suit different hunting scenarios and personal preference—for example, Red Hot and Iron Red are popular for spotting warm game against cooler backgrounds.
