Feature 1COMPATIBLE SYSTEMS: Compatible for Windows 2000, for Win XP, for Win ME, for Win 7/8/10, for OS X, for Linux. 2CONSTRUCTION AND LAYOUT: Sturdy construction with textured steel and minimalist top. Rubberized feet in the corners underneath the keyboard. Sturdy braiding cable with durable stretch effectively reduces external resistance. There are 22 keys. There is also a blue LED NumLock indicator. 3EASY TO USE: No driver required, plug and play, only one USB port is needed to provide you with the most stable USB connectivity. 4LONG LIFE: The numeric keypad is rated for over 50 million pressures, which exceeds the standard operating expectations of membrane keyboards. 5NOTE: This numeric keypad is not fully compatible with for OS X. The function keys do not work, while other keys work fine.Item Type: Mechanical Numeric KeypadMaterial: ABS, MetalConnection: USBNumber of Keys: 22 Keys .wang-edit-text{ font-family:'Arial' !important; } .wang-edit-text table { border-top: 1px solid #000; border-left: 1px solid #000; } .wang-edit-text table td, .wang-edit-text table th { border-bottom: 1px solid #000; border-right: 1px solid #000; padding: 3px 5px; } .wang-edit-text table th { text-align: center; }Package List1 x Numeric Keypad1 x Instruction Manual