KLH Ultimate One Headphones, 50mm Pure Beryllium Drivers, Zebrawood The Ultimate One Headphones feature an over-ear, open-back design with a 50mm pure beryllium driver. The headphone headband and ear pads feature soft lambskin inner sections for ultimate comfort, with cowhide leather outer sections for lasting durability. The Ultimate One Headphones have real wood ear cups are available in zebrawood ($299.99). The frequency response is rated at 18Hz-22kHz. Features And Specifications - 50mm Pure Beryllium Driver. Headband & Earpads use premium lambskin and top-grade cowhide leathers with dual-layer memory foam for ultimate comfort and maximum durability. Solid, Real Zebrawood earcups for eye-catching beauty and acoustic integrity. Extremely comfortable and lightweight at only 12 ounces/340grams. 32 Ohm impedance 97 dB sensitivity Frequency response: 18 Hz to 22kHz /- 3db 108 db SPL 2 meter detachable, 3.5mm pure silver-litz braided cable (¼” adapter included) KLH Branded, hard-sided black leather travel case plus a luxuriously soft velour carry bag. 2-year Warranty