Svpro smart watch sports bluetooth speaker has soft adjustable wrist band design which compatible for all ages.It can tell you the time, count the time and alarm the time for you while doing sports. It will free your hands from your phone or radio or speaker. It can even be used as a selfie timer. You only need to wear it on your wrist, and enjoy your sports life more freely and breezily. Specification: Output power:3W THD:10% Sensitivity:83dB+/-3dB Noise-signal ration:80dB Charging voltage:DC-5V500mA frequency respond:120Hz-20KHz Bluetooth parameters:Bluetooth V3.0+EDR Precautions and notes: Please charge for at least 2 hours before first time using Playing duration relates the the playing sound volume The device is not allowed to place in hight temperature ,wet environment ,must not be caught in rains or hit with strong impact. Bluetooth function of this device will be different due to the matched device bluetooth function ,may be different in compatibility or self timer function . The device could be charged by DC 5V power adapter or computer USB port,red light will be on charging. When the device is powerd on ,in standby mode the battery can last for 2 days when it is connecting to matched devices. It is compatible issue if it cannot read the TF card or bluetooth deos not match. If the device is in low battery status ,there will be reminding sounding(meantime the battery icon will quickly flash)to inform to charge in time ,at this moment the sound volume will reduce 50% automatically to avoid powering off immediately.