Built in Li-ion battery, rechargeabe via USB cable.     
Micro 5Pin USB 3.0                                                          
LED for bluetooth connection                                   
Bluetooth V3.0, support Apple & Windows system                                                    
2) Electrical specification ﹕
A. Working  frequency: 2.400GHz-2.483GHz
B .Working distance: 10m
C.Battery: Polymer lithium ion battery (3.7V)  volume:180MA
D.Charging time: 2 hours, Uninterrupted working time: 100-hour                                                               
E.Standby 90 days
F. Working current: <2mA @ 3V
G. Sleeping current: <50uA @ 3V
H. Sleeping mode: The keyboard automatically enter sleep mode when you are not using in 20 minutes.
I. Sleeping waking way: To press any key