Sony MDR-XB600 - Extra Bass Foldable Premium Headband Headphones (Certified Refurbished) This Certified Refurbished product is factory refurbished, shows limited or no wear, and includes all original accessories plus a 90-day warranty 40mm diaphragms for deep, powerful bass (4-24Hz) Direct vibe structure for superior bass response Pressure relieving foam ear pads for long-term comfort and sound isolation Dual folding design folds compact for storage