Exclusive Monster iDock port eliminates headphone cords and delivers great sound, iPod Shuffle docks directly into headphones, Wrap-around design: no need for clips, armbands, or pockets, Easy access to all iPod Shuffle controls, Folds for compact storage, Featherweight for extended listening comfort (1.6 oz without Shuffle), Sensitivity: 110dB/mw, Impedance: 32 ohms+ 15% @ 1KHz, Distortion: > 5% A 1KHz, Max Power Rating 20mW.