The num lock function is independent of any other keyboard that are currently connected.The mechanical switch keypad can ensure a fast response.Compare with the other standard keypad, the 21 keys extended some keys at the top, contain Esc,Tab,Back Space,and FN keys.21 keys enhanced mechanical numberic keypad has 17 numeric keys and 4 additional keys,including tabescand FN. By simultaneously pressing the FN key and another key, you can input parentheses, an equal sign, currency symbols, or activate the calculator.Mechanical numberic keypad has 4 backlight model and 6 backlight brightness can be adjusted. By simultaneously pressing the FN key and another key, you can change the backlight and brightness.21 keys mechanical numeric keypad is suitable for laptop users,banking, financial securities, business workers or Used with 87 keyboards, 82 keyboards, 68 keyboards, 61 keyboards and other keyboards without numeric section.size:127x86x38 mmMaterial:ABScolour:BlackPackage Contents:1 * numeric keypadOnly the above package content, other products are not included.Note: Light shooting 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.