2.4G Wireless Numeric Keypad Model: NK606 SPECIFICATION NOTE Model: NK606 Number of keys: 35 keys Working voltage: Battery capacity: Working distance: Size: inches(Max) Key switch life: 10 million strokes times Working frequency: 2405MHz~2467MHz Compatibility: Windows XP/Vista/7/8/ 10/Android / i Mac 1. Please charge for 10 minutes before first usage. 2. When the numeric keypad is not been used for long time, please power off. 3.