Portable speaker bluetooth speaker effective output 15 watt system 2 way system speaker system 21 system principle active frequency response 70 20000 hz amplifier type digital power supplies rechargeable battery usb battery life 9 h colour blue front colour black functions streaming speakerphone function nfc control feature bluetooth pairing number of full range drivers 2 bass chassis 51 mm number of passive radiators 1 analogue input 35mm