... 2.Easy to handle, built-in BTL stereo amplifier, compatible with different audio device such as laptop, mobile phone,ipod , ... for power,it's small and light,easy to carry.4.Color for option:red ,black,or as customers' requests ... 2 Total Harmony Distortion: <1% Driver Unit: 2 Inch*2 4Ω Frequency Response: 150Hz-20 KHz USB Voltage: 5V (500mA) ... deposit by T/T or the original L/C. Mini speaker for laptop