In the cold winter months, ambient temperatures may not be condusive to beer and wine fermentation. Enter the Brew Belt! This handy device wraps around a fermenter and can maintain a temperature of 75F for up to 8 days. It comes with two different springs which will help you wrap this around almost any standard fermenter. This is a 15v device that plugs into a standard 110v outlet. Will work with standard 5 and 6 gallon plastic carboys, 6.5 and 7.9 gallon plastic fermenting buckets. The manufacturer does not recommend using this with glass fermenters.