AERIAL7 Mayrhofen Red Beanie w/ Built-in Headphones Engineered to deliver the highest-quality listening experience from your mp3 player or other music device. Built-in microphone for use with iPhone, BlackBerry, and other mobile devices. The Sound Disk is only 8.5mm thick and delivers a full spectrum sound experience. Driver Diameter: 35mm, Frequency Response: 20-20KHz Adapters: 3.5mm ~ 3.5mm iPhone