GUIDE TD421 LRF 384x288px 25mm Thermal Monocular (with Rangefinder) from the GUIDE brand — a compact and professional TD series thermal imaging device with a built-in laser rangefinder (LRF), laser designator, and powered by a replaceable 18650 battery. The model is equipped with a 25mm lens with a moderately wide field of view, a second-generation sensor with 384x288 pixel resolution, and enhanced thermal sensitivity: the NETD value is reduced from 50 to 35 mK, ensuring clearer detection of thermal contrasts. The maximum detection range for heat sources reaches 2400 meters, making the TD421 LRF an effective tool for long-distance observation.

Design Features

• Built-in laser rangefinder — up to 600 m
• Laser designator — up to 200 m
• Focus ring on the lens for quick sharpness adjustment
• UNC 1/4-20 tripod mount
• Interface for attachments and additional devices
• Diopter correction adjustment from -4 to +2
• Two types of interchangeable eyecups for comfortable observation
• Replaceable 18650 battery for quick field replacement

Detection and Recognition

Detection and recognition ranges for typical targets, demonstrating the practical capabilities of the device in field conditions:

• Vehicle (2.3 m x 2.3 m): detection — up to 2400 m, recognition — up to 1000 m
• Human (1.8 m x 0.5 m): detection — up to 1000 m, recognition — up to 500 m
• Deer (1.5 m x 0.5 m): detection — up to 820 m, recognition — up to 400 m
• Wild Boar (0.9 m x 0.7 m): detection — up to 620 m, recognition — up to 300 m

Technical Specifications

• Sensor: Uncooled VOx array 384 x 288 px (12 μm, 50 Hz)
• Spectral range: 8 μm - 14 μm
• Thermal sensitivity (NETD): ≤ 35 mK (at 25 °C)
• Lens: 25 mm, F1.1
• Angular field of view: 10.4° x 7.9° (horiz. x vert.)
• Optical magnification: 1.9x
• Digital zoom: 1x, 2x, 4x
• Display: 0.23" FLCOS with 640 x 400 px resolution
• Color palettes: Black Hot, White Hot, Red Hot, Iron, Blue Hot
• Battery type: 18650 x1 rechargeable battery (replaceable)
• Operating time: up to 10 hours on a single battery
• Housing protection: IP66 (dustproof and protected against powerful water jets)
• Interfaces: Wi-Fi, Bluetooth, USB Type-C

Package Contents

• GUIDE TD421 LRF Thermal Monocular
• 18650 battery, 3350 mAh (1 pc.)
• USB Type-C charging cable
• USB Type-C multimedia cable
• Charger for 2 batteries
• Wrist strap
• Interchangeable eyecup
• Soft case for storage and transport
• User manual

Dimensions and Weight

• Thermal imager dimensions: 151 x 76 x 74 mm
• Thermal imager weight: 356 g (405 g with battery)
• Package dimensions: 264 x 138 x 130 mm
• Package weight: 1.24 kg

The GUIDE TD421 LRF is ideal for hunters, security professionals, guard services, and professional users who require a reliable, compact device with a rangefinder, high sensor sensitivity, and a wide range of interfaces for connectivity and data transfer. The UNC 1/4-20 tripod mount, replaceable 18650 battery, and flexible optical settings make this monocular versatile for wildlife observation, tactical use, and night operations.

Technical features such as the 8–14 μm spectral range, NETD ≤ 35 mK, IP66 protection, and five color palettes enhance the device's versatility and ensure convenient use in various weather conditions and observation scenarios.

Other products in this category can be found here Thermal Monoculars