The HD661 is a closed-back, circumaural headphone which is excellent for live sound monitoring application because of its sound profile of depth of sound field. It's also suitable for studio and broadcast. Although suitable for a very wide range of applications, the exceptional attenuation of external noise of the HD 661 makes it particularly useful for use in a high noise environment. The balanced, high definition and clear sound of the HD661 assures that a professional sound engineer can have full confidence when recording or monitoring. Its patented sturdy headband structure provides long-lasting durability even in challenging conditions, yet its light weight and optimized mechanical pressure provides long-term wearing comfort.