Sennheiser RS 140 Wireless HiFi Headphone with Dynamic Compression System (Discontinued by Manufacturer) Wireless, rechargeable hi-fi headphones with switchable dynamic compression system Maximizes clarity of spoken voices to enhance TV sound or assist people with moderate hearing loss Intelligent auto tuning and automatic signal control ensure high-quality reception Transmission range of up to 150 meters; 18 Hz to 21 kHz frequency response Includes NiMH battery pack, charging stand, transmitter, and 1/4-inch plug adapter