Product Featire : 1. Model No: BT-90 2. Standard Micro USB Charger 3. Available usage within 10 meter 4. Modulation System : GFSK 5. Working Voltage : 3.0-4.2V 6. Working Current : 7.Standby Current : 8. Sleeping Current : 9. Charging Current : >200mA 10. Standby : > 100 day 11. Charging Time : < 2 hour 12. Lithium Battery Capacity : 110mA 13. Sustainable Working Hour : > 40 hour 14. Lithium Battery Life : 3 year 15. Lithium Battery Size : 3.0*23*23cm 16. Force to Key : 60 +/-10g 17. Key Life : 300 million click 18. Working Temperature : -10 to +55 degree