Sennheiser RS 4200. Ear coupling: intraaural, Headphone frequency: 50 - 16000 Hz, Headphone sensitivity: 125 dB. Connectivity technology: Wired. Dimensions (WxDxH): 115 x 95 x 145 mm, Weight: 50 g. Battery recharge time: 3 h, Battery technology: Lithium-Ion (Li-Ion). Package dimensions (WxDxH): 200 x 20 x 135 mm