Polar Fusion Acoustic, Tri-Season Ear Warmers Featuring Stereo Headphones and Warm Fleece Ear Pockets. One Size. Non-Traditional Ear Muffs. High quality headphones with neodymium magnets maximize sound quality. Plugs into any portable stereo/MP3 players. Exclusive sound doors flip open to help you hear sounds coming from behind more clearly. Wrap-around headband will not interfere with open-ear helmets, hats, glasses or hairstyles. Non-Slip, lightweight and comfortable ear warmers stay in place for extended wear during activities. Made in USA with USA and internationally sourced components.