Koss HB70 Streetstyle Cordless Infrared Headphone System (Discontinued by Manufacturer) Frequency response 30-15,000 Hz Dynamic Element Stereo phone for Extended Frequency Response Ideal for Home Theatre and Video. Connectivity Technology: Wireless Frequency response 30-15,000 Hz Dynamic Element Stereophone for Extended Frequency Response Ideal for Home Theatre and Video Connects to Most Audio, and Video Systems Provides 20 Square Feet of Convienient Cordless Coverage