Denon AH-NC800 Advanced Noise Canceling Headphones (Black) Denon's exclusive dual noise canceling technology reduces ambient noise by up to 99% Large 42mm dirvers and Denon's Acoustic Optimizer technology for balanced, uncolored sound Hybrid Aluminum Housing Material reduces ear cup resonance to maximize fidelity Noise cancelling circuit powered by a single, widely available AAA battery delivering up to 40 hours of listening 3D-contoured soft protein leather covers over super-soft compliant foam pads provide maximum acoustic isolation along with supreme comfort