... absolute superiority! Transfer rate: USB2.0 interface, built-in lithium battery, 5 hours of playback Play Format: Support MP1/MP2/MP3 ... WAV and other audio formats; Adjustable headset: Harmonic Distortion ≤ 0.1%; frequency response :20-20KHZ; signal to noise ratio: 90Db; ... structure, do not worry about headphones off. MP3 Glasses Description: 1. Supports multiple audio formats: such as WMV, ASF, MP3 ...