It prevents condensation by warming up the lens on a camera or telescope. The dew heater strip has three heating levels: low, medium and high. It runs on external USB power, which can be used for a long time in the open air. Made of high quality material, the strip has the characteristics of rapid heat transfer and good heat preservation effect. Besides that, it adopts low temperature cable that can withstand temperature as low as -40C so the cable is sustainable in cold environment. Moreover, the hook-and-loop fastener makes it fast and easy to attach and remove from your gears. Product HighlightsSpecially designed for camera lenses and telescopesPrevents condensation by warming up the lens on a camera or telescopeWith low, medium and high heating modesRuns on external USB powerAdopts low temperature cable can withstand temperature as low as -40CHook-and-loop fastener makes it fast and easy to attach and removeSpecificationInput: DC 5V 2AHeating Level: low, medium and highCable Length: approx. 1.5mPower Source: USBPackage IncludesDew Heater Strip x 1