High sound quality headphone developed specifically for professional DJs and other critical monitoring applications. It is designed to clearly emphasize the beat of the music as well as capturing its more subtle nuances. Featuring 51 mm (2"?) extra-large diaphragms and high-energy Neodymium magnets, the HD631 series presents an excellent, balanced sound profile while giving an extra punch to the low end frequencies. Even the most critical professional DJ or audio professional will find the HD631 series ideal for delivering the exact sound performance they need to do the job.