metal USB speaker with FM radio function USB power or with lithium battery built-in mp3 player welcome OEM service speaker metal usb speakersParameter:1, Output power: the RMS 2.4 W * 2 = 10 THD (F = 1KHz),2, Frequency response: 80Hz 20KHz ~3, Signal-to-noise ratio: more than 80dB4, Resistance: 4 ohm5, Power supply: DC5V or USB + 5V battery parameters (machine)6, Nominal voltage: 3.7 V7, The ...