Sennheiser RS 120 , Wireless Headphones, Rechargeable wireless headphone with RF transmitter, Up to 100 m range, Detailed sound reproduction with powerful bass, On-ear, Open design, Max. SPL: 106 dB SPL, Impedance: 24 Ohm, Frequency response: 22 - 19,500 Hz, Weight: 230 g, Includes TR 120 II transmitter with audio connection cable, 2 rechargeable batteries type AAA, Ni-MH, 1.2 V, power adapter and 6.3 mm jack adapter