Sony MDR-IF140K. Wireless range: 7 m. Headphone frequency: 18 - 22000 Hz, Magnet type: ferrite, Driver unit: 30 mm. Compatible battery sizes: AAA. Dimensions (WxDxH): 152 x 72 x 38 mm, Weight: 125 g. Depth: 72 mm, Volume control: Digital, Width: 152 mm