The main functions that a thermal imaging camera must have, regarding the purpose of hunting, are recording and measuring the distance. Additional functions include accurate temperature measurement and the flexibility to be mounted on drones. Also critical in a thermal imaging camera is the detection distance and the possibility that it has a built-in rangefinder. The main types of this category are thermal imaging monoculars and binoculars and thermal imaging cameras that can be attached to daytime optical devices (terrestrial scopes).