【Enhanced Heating with FPC Technology】 Designed with FPC (flexible printed circuits), this lightweight yet durable lens heater uses polyimide films as the insulator for reliable dielectric performance, and thermofoil as the heating element for improved thermal conductivity and higher heat transfer efficiency to quickly and evenly warm up your lens. Note: The lens heater is bendable but cannot be folded | 【Effective 16"/400mm Heater Length】 Eliminate dew, fog, and condensation with our specially crafted lens warmer during cold weather photography. For optimal performance and even heating, it is recommended to use on lenses or telescopes with a circumference of up to 16"/400mm and a diameter of 127mm | 【Safe 5V 2A USB Power Supply】 Through the 6ft/1.8m USB cable, the lens heater can receive power from any USB power source with a 5V 2A output and feature overheating/overvoltage protection for safe use. A regulator offers 3 temperature levels (High: 125.6°F/52°C; Mid: 113°F/45°C; Low: 98.6°F/37°C) for different environments | 【Touch Fastener Attachment】 Thanks to the flexibility and thinness of the FPC, the heater can easily wrap around your lens via the touch fastener. Note: The heating area length is 16"/400mm, and the total length is 22"/550mm including the touch fastener | 【A Multifunctional Heating Tool】 As a multipurpose heater with a whole length of 22"/550mm (including the fastener part), it can also keep your coffee mug warm in winter (use with care). Can also be used on telescopes, scopes, etc