Mammoth is our fashionable, oversize knit beanie. Available in Antique, Grey and Purple/Black Striped, this chunky cable-knit beanie is lined with stretch cotton material and will keep you warm and stylish through winter. Rock out in style with AERIAL7?s Sound Disk Beanie, the perfect accessory merging technology and fashion. Adjustable speakers allow the flexibility to change their placement based on your activity. Slide the disk over your ears to fully engage or position the disk partially behind your ears to be aware of your surroundings. FEATURES - 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. TECHNICAL SPECIFICATIONS - Driver Diameter: 35mm - Impedance: 32Ω - Frequency Response: 20-20KHz - Sensitivity (S.P.L.): 100±3dB (at 1KHz) - Input Plug Diameter: 3.5mm - Adapters: 3.5mm ~ 3.5mm iPhone