54 dB. Features Auto Scan frequency Adjustment. Charging Base Transmitter Unit with Docking Stand for Headphone, Ideal For Storing, and Charging The Headset After Use. Automatic Level Control (ALC) with Auto ON\/OFF Control. Ergonomic Headphone Design with Soft Leatherette Earpads For Longer Listening Comfort. 10 Hour Headphone Operation on a single charge. ECO-Friendly Power Supply for reduced STANDBY power consumption. Rechargeable AAAx2 NiMH batteries are included (User-Replaceable). Dimensions: Transmitter: 184 x 150 x 54 mm. \/ Receiver: 200 x 90 x 110 mm. Weight: Transmitter: 406 g \/Receiver: 256 g. Accessories included: AC-ADAPTOR \/ 6.3mm (M) to 3.5mm(F) Adaptor stereo \/ 3.5mm (F) Stereo to RCA (M) Short Cable Adaptor \/ RCA (M) to 3.5mm(M) Stereo AUX Cable (1.5M length) \/ AAA Rechargeable NiMH Battery (1.2v, 550mAh) x 2pcs ""/>