EOTech Thermal Vision instruments can be used during the day as well as the night, and regardless of the surrounding weather condition. They use the highest thermal sensitivity and depend on infrared light (heat) emissions to identify humans, animals, and vehicles at long distances.EOTech Night Vision devices, on the other hand, detect radiation on a wavelength that’s not perceptible to the human eye and then convert it to an image that's visible. Their mode of working is dependant on image intensification, thermal imaging and active illumination.