Sennheiser HDR 120 Headphones, Extra Wireless Headphones for RS110 and 120 Systems (charger not included)/Open, stereo, supra-aural, wireless RF headphone/Detailed, analytical sound reproduction with strong bass response; Suitable for all types of modern music and TV application/Wireless freedom with reception through walls and ceilings/Very lightweight headphones, extremely comfortable to wear.SPL for peak deviation: 106 dB/Impedance