Aluminum numeric keypad $ 21.60 Material: Aluminum alloy + ABS plastic Support system: Windows, iOS, Android Number of keys: 34 keys Wireless/Bluetooth solution: Broadcom (BCM20730) Bluetooth version: Bluetooth 3.0 Keyboard life: (number of keystrokes) 5 million times Response speed: 5 milliseconds Wireless/Bluetooth transmission distance: 10 meters Working current/voltage: 2mA/3.7V Built-in lithium battery: Yes Battery type & capacity: polymer soft pack lithium battery 302323-110mAh