Folding high performance noise cancelling wireless headset in EVA zipper case. Power/Technology: Rechargeable Lithium-Ion battery: 3.7V/250 mAh; Speaker diameter/driver: ?40mm; Sensitivity: 105dB±3dB; Impedance: 32?; Frequency Response: 20Hz-20KHz; Active cancellation: up to 15~20dB between 100~1kHz; Frequency range microphone 20Hz—16 kHz; Sensitivity microphone: 40±3dB; Transmit Range: 10m (30 ft); Wireless Version: 4.1 Features soft PU headband and control buttons on side of headset. Compatible with most audio equipment with wireless capabilities Playback time: up to 10 hours, depending on use Item must be charged prior to first use. Charge time varies by device, minimum charge time 2 to 3 hours Charging cable and instructions included. FCC Approved WARNING: Refer to the item manual for safety and warning instructions.