Specification: support a2dp 1.3, avrcp 1.6, hfp 1.6 signal-to-noise ratio 80db a-weighted bluetooth transmitter power 0 to 9dbm bluetooth transmitter frequency range 2402mhz to 2480mhz battery charge time 3 hours battery type 22.2wh rechargeable battery bluetooth version 4.1 power supply 19v 3a usb charge out 5v/2.1a ( 5v/0.5a when playing music) frequency response 50hz-20khz (-6db) rated power 4x25w (ac mode) bluetooth transmitted modulation gfsk, π/4 dqpsk, 8dpsk music playing time up to 8 hours (varies by volume level and audio content) what's in the box: 1 x harman kardon go + play 1 x power adaptor 1 x quick start guide 1 x warranty card 1 x safety sheet free delivery in city centre. cash on delivery /pickup