MD 828 wireless bluetooth headphone has up to 10 hours playback capacity, play music on TF card, support MP3 / WMA files, support up to 16GB memory card,speaker diameter 40mm, speaker impedance 320hm, speaker sensibility 112db+/-3db, charging time 4 hours, decoding range 8-320 Kbps, radio frequency range 87 - 108 MHz.