DHS-1 Dew Heater Strip is specially designed for camera lenses and telescopes. | It prevents condensation by warming up the lens on a camera or telescope. This strip fits outside diameters less than 4.3" and has three heating levels: low, medium and high. | The heating time can be set for 15mins, 30mins or 60mins. Made of high quality material, the strip has the characteristics of rapid heat transfer and good heat preservation effect. | It runs on external USB power, which is convenient for use in the open air. | the hook-and-loop fastener makes it fast and easy to attach and remove from your gears.