The Alpha Optics AO-4431/4461 thermal imaging weapon sight is one of the most advanced scopes in its class. Displaying the thermal differences in the scene, the high-performance thermal imaging system of the device provides round-the-clock, all-weather detection and discrimination of heat-generating objects, including those that are hidden. The attachable distance measuring unit with the distance readout on the device display enables to estimate accurately the target distance. Rubber coated enclosure of the Alpha Optics AO-4431/4461 features conveniently located control elements. The device is designed with the shutter-less calibration technology enabling quick start and continuous image without stops and delays. The specially developed control electronics of the device works without complicated menu. Ballistic corrections and four memory slots enable saving zeroing profiles for different distances and different types of ammunition. Intuitive menu of the device enables to select the reticle type, its colour and brightness, as well as to adjust manually the image brightness and contrast, the core thermal sensitivity and other parameters. Attachable external power supply increases significantly the runtime of the sight. The AO-4431/4461 is effective at long ranges regardless of light and weather conditions, such as in total darkness or through smoke, haze, fog, and light rain.