Koss Pro4AA headphones set the standard for full size professional headphones. They were introduced in 1970 as the first dynamic headphones to deliver true full frequency and high fidelity performance with impressive noise isolating capabilities. Retired in the late '80s, Koss swiftly returned the Pro4AA headphones to its product lineup due to overwhelming popular demand. They have since remained a staple of studio headphones in the radio and recording industries. Koss Pro4AAs meet the stringent demands of broadcast and recording professionals who require reliable equipment and superior performance. The full size professional headphones keep unwanted sounds out while letting every note in. Whether you're a sound professional or an audiophile, Pro4AAs deliver superior isolation, accurate reproduction and sound intensity, and the excitement of a live performance with every recording. Connecting with your music has never sounded so good.