Sennheiser RS 165 RF Wireless Headphone System - Black Contents: Come with accessories in retail box.New Opened Box Condition. Closed back, circumaural headphone system with excellent digital wireless audio transmission delivering range up to 30 meters(100-foot). Connectivity Technology: Wireless High-quality Sennheiser transducers and a selectable Bass Boost mode for exceptional sound. Range-Up to 30 m,Max. sound pressure level 106 dB at 1kHz, 3% THD. Signal-to-noise ratio - typ. 85 dBA at 1 Vrms . Frequency response - 18 - 21,000