Hyperion Adjustable Heat Temperature LiPo Battery Bag is ideal for use in winters, LiPo can lose up to 40% of their capacity when used in cold weather. This of course will drastically shorten flight times and performance too. Now save your LiPo batteries from the winter cold with this superbly built LiPo warmer. A must have for the RC enthusiast who wants to keep flying/driving in cold weather/climate and also for competition pilots/drivers looking to squeeze every ounce of capacity from their battery for optimum performance, even in warm ambient temperatures. No programming required just plug in an old LiPo and select from the 3 modes Low/Medium/High as per temperature requirement (max 50degree) from 25C ~ 50C (77F~113F). The sealable bag is lined with a heat reflective material, helps keeps your LiPo snug and ready to use.