Wired model, can only be used with a USB cable. Setup tool is under Windows system; after decompression, connect a TYPE-C cable to configure. Maximum number of characters that can be set continuously is 5, same as the 3-key, 1-knob wired acrylic keyboard. Keyboard shell is made of aluminum alloy with polished edges on both sides; keycaps are made of ABS material. Color: Black Material: Aluminum Alloy+ABS Package Contents: 1 * 2-key Customizable Numeric Keypad Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.