Mmuss Wireless Bluetooth Sports Music Beanie Knit Headphone Speaker Hat with Built-in Mic - Black Bluetooth Version V4.0+EDR. Compatible with all Bluetooth devices Washable beanie after removing headphones Speak directly while wearing the beanie without having to deal with wires or even taking it off while doing everyday tasks Built in rechargeable Li-Ion battery provides up to 6 hours of playtime. (USB charging cable included) one size beanie fit all heads