121 Key: 21 key mechanical numeric keyboard, key switch structure is mechanical, Mechanical Linear Action Switch structure, excellent feel, quiet operation. 2Plug and Play: plug and play, USB interface, no driver required, compatible with multiple systems, suitable for special equipment such as bank securities, financial accounting, station gates, etc. 3Laser Engraved Characters: Laser engraved characters are not easy to be erased, the keys have a long life, and the keycaps are comfortable. The life of the button is >50 million times, and the four large antislip feet at the bottom can effectively avoid shaking or falling during use. 4Function: Splashproof, Mechanical Linear Action Switch, with Back Space backspace key, easy and fast correction. With Esc key, with Ctrl key, with Alt key, with NumLock key, with Enter key, with +*/ key, with Del key. 5Scope of Application: Number pad is suitable for notebook computer users, suitable for bank securities, financial accounting, supermarket cashiers, industrial computers, industrial computers, special computers, server input, general and commercial purposes, and industrial purposes. Item Type: 21KeyNumericKeypad Material: Plastic Model: DX 21A Keys: 21 Keys Cable Length: Approx. 1.4m / 1.5yd Type:Linear Action Switch Mechanical Numeric Keypad Key Structure: Mechanical Linear Action Switch Button Life: >50 Million Times Keyboard Travel: Approx. 4mm / 0.2in Current: 60mA Function: Splashproof, Mechanical Linear Action Switch, with Back Space backspace key, easy and fast correction. With Esc key, with Ctrl key, with Alt key, with NumLock key, with Enter key, with +-*/ key, with Del key. The multi function 21 key design is simple and convenient. Types of Use: Bank Securities, Financial Accounting, Supermarket Cashiers, Industrial Computers, Industrial Computers, Special Computers, Server Input, Broadcasters, General and Commercial Purposes, Industrial Purposes Support: For DOS, for Windows 95, for Windows 98, for NT, for ME, for 2000, for 2003, for XP, for VISTA, for Windows 7, for Windows 8, for Windows 10, for Linux, for OS X, etc. 1 x 21KeyNumericKeypad