Features: 1.Using Bluetooth 3.0, stable wireless connection and the transmission distance is about 10m / 32.8ft. 2.Compatible with multiple systems, small size, easy to carry, long?lasting power, compact in size and convenient to use. 3.Stable transmission, plug and play makes it suitable for notebook and desktop computers. 4.Simple design and good hand feelings of the key cap, streamline modeling, bringing you wonderful using experience. 5.Made of aluminum alloy material is durable and not easy to deform, can effectively resist oxidation and rust, long service life. specification:Item Type: Numeric Keypad Material: Aluminum Alloy + ABS Number of Keys: 28 Input Interface: Bluetooth 3.0 Operating Voltage: 3.3-4.2V Solution: Megawatts Operating Current: < 2.5mA Built-In Battery Capacity: 140mAh lithium battery Standby Current: < 0.5mA Compatible System: for IOS/ for Android / for Windows PackageList: 1 x Numeric Keypad 1 x Manual 1 x Charging Cable