"The shirts utilize ambient sound as a catalyst to produce electric voltage, and were rolled out just in time for the Glastonbury Music Festival in Britain. Developers hoped that the shirts would offer a convenient, eco-friendly way for festival goers to charge their phones while they're rocking out away from the grid. The material used in the shirts is made from a product called piezoelectric film, which is capable of transforming sound waves into an electric charge via the compression of interlaced quartz crystals.