mini speaker with built in amplifier 1.Phone,MP3,iphone,PCspeaker 2.In battery and external battery slot 3.FM,Clock,alarm SU- ... 22 mini speaker with built in amplifier FM,clock,alarm Description:1.Mini speaker built in amplifier support any MP3 music from ... ~18KHZ 5.Impedance:4Ω6.3.5mm Stereo Audio Jack7.Built-in 500MAH rechargeable Li-ion battery8.Rechargeable time:2-3h9.External ...