Sennheiser HDR-120 wirelesss headphone without transmitter - Additonal headphone for wireless headphone systems RS 115, RS 117, RS118, RS 119, RS 119-II, RS 120, RS 120-II, RS-127, rechargeable wireless headphone, up to 100 mrange, detailed, analytical sound reproduction with strong bass response, on-ear design, open back, impedance: 24 ohms, 106 dB SPL, frequency response: 22 -19500 Hz, weight 230 g