Profile: Koss Corp. specializes in providing stereophones. Our stereophone types include full size, portable, streetwise, earbud, wireless and noise cancellation headphones. The UR18 delivers digital quality sound in an ultra-lightweight design for listeners. It features dynamic elements for a wide frequency response from 25-15,000 Hz. Closed leatherette ear cushions form a light seal around the ears, enhancing bass frequencies. An adjustable headband accommodates all head shapes and sizes for maximum comfort. Wireless headphones eliminate the cord altogether. They can require a transmitter that must be connected to the source. They are available in different technological platforms including radio frequency (RF) that transmits an RF signal through walls & ceilings and infrared (IR) that transmits an IR signal within line sight of transmitter.