KRK KNS 8400 On-Ear Closed Back Circumaural Studio Monitor Headphones with Volume Control Detachable in-line volume control Voiced to remain true to the character of KRKs class leading studio monitors, developed with 25 years of years of experience in studio sound. The latest reference quality frequency response for closed-back, circum-aural dynamic headphones. Newly developed headphone acoustical system bringing a new level of headphone performance for the first time. Utilizing the latest in acoustic memory foam technology this ensures class leading performance in both reproduction and isolation.