Manhattan 178693 Wireless Heaphones Total harmonic distortion (THD): 0.1% at 1 kHz Sound pressure level (SPL): 95 dB Frequency response (headphones): 20 Hz C 20 kHz Battery: internal rechargeable Li-polymer On-ear, behind-the-head design with soft, padded ear cushions for maximum comfort Delivers high-quality wireless streaming from Bluetooth-enabled devices up to 30' away Built-in, recessed microphone Lithium polymer battery provides up to 20 hours of playback time (400 hours of standby time) Micro-USB charging cable included Integrated on-ear controls allow you to easily adjust volume, play/skip tracks and answer calls