Elftear Numeric Keypad 19 Keys Retractable USB Cord Number Keypad for Mac Windows XP Laptop Desktop PC USB Keyboard comes with 19 keys of 0-9 number keys, 000,Del, Enter, Back Space, Num Lock, + - * /. Digital keyboard with 19 keys, Ideal for notebooks without a number pad Keys operate smoothly and quietly. Space saving ergonomic spill resistant 19 key USB numeric keypad with back space and "00" keys for improved productivity. USB wired connection with storable USB connector hides cable to safely transport and reduce cable clutter, Simple plug and play installation. If you use MAC, you can't use the Num Lock keypad. If you use the Windows series system, Num Lock keypad in normal work, Windows 32/95/NT not support USB device.