Features: 1.BLUE SWITCH: Supports multiple backlighting modes. By pressing the FN key and another key at the same time, you can change the backlight and brightness. The professional mechanical blue switch with tactile collision and audible clicks, which provides fast and precise key presses. 2.PLUG IN USE: Fully programmable keys, which wired to your computer and supports NumLock, ESC, Tab, Delete, etc. The keypad with shortcut keys to open computer calculator directly. 3.LONG LIFE: 50 million keystrokes, key characters that won not fade, ABS construction that stands up to harsh conditions for a long life. 4.ERGONOMIC DESIGN: This mini keyboard features stepped keycaps that easily fit your hands and prevent fatigue. Spring loaded ergonomic design cares for your wrists. 5.21 KEYS: 21 keys mechanical numeric keypad is suitable for laptop users, banks, finance and securities, business people or other keyboards without numeric part. Small and lightweight, easy to carry. specification:Item Type: Mechanical Numeric Keypad Material: ABS Model: K21 Interface Type: USB Switch: Blue switch Number of Keys: 21 Connection Method: Wired Support System: Support for Windows, for Android, for OS X and other multi system PackageList: 1 x Keyboard 1 x Instruction Manual