Keeps your head warm, while also listening to music or making calls hands free via the newest Bluetooth v5.2 technology. The hat has a built in microphone that picks up calls directly and has excellent sound quality stereo speakers. These have a rechargeable 200 mAh battery. Standby time is 500 hours, play time is 24 hours at max volume and charge time is about 2 hours. This hat comes in many great colors and one size fits most adults.