B925BL Bluetooth 4.2 wireless connection function up to 10 meters Built-in 55mah rechargeable battery for up to 4 hours of music listening, and charging only takes one hour in-ear and ear-hook design, never afraid to drop out of the line and microphone when exercising ,2G-2.480G plug type USB noise reduction CVC Bluetooth Bluetooth is Bluetooth version V4.0 Bluetooth protocol HFP / HSP / A2DP / AVRCP transmission range 10 meters (accessible space)