Snipers also have to take into account their appearance under infrared (IR) light, because many armed forces now employ thermal vision devices that work in this spectrum of light as opposed to normal night vision devices that simply gathers and intensifies normal light. Some clothes or equipment stand out when viewed with thermal vision devices and care has to be taken in selecting and covering equipment so that the sniper is not readily visible when viewed under infrared light. Clothing or equipment not readily visible under infrared light is said to have a "low IR signature". Plastic or foil "thermal blankets" can also be employed to cover a sniper and their equipment, but these, in turn, must then be camouflaged (often local foliage or material).