AKG K550MKII Sealed Headphone New Generation 50mm Diameter Dynamic Driver Adopted Reference Black K550MKIIBLK Highly accurate AKG sound Closed-back design for a fully personal listening experience 50mm driver size to enjoy outstanding sound from any device Lightweight and comfortable fit for hours of continuous listening 2D-Axis folding flat mechanism for easy storage and transportation 3.5 to 6.3mm adapter