The num lock function is of any other keyboard that are currently connected.The mechanical switch keypad can 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. Mechanical numberic keypad has 3 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. Applicable models: general Type: Numeric keyboard Number of keys: 21 (keys) Switch: brown Whether to support plug and play: support Connection with computer: wired Whether there are multimedia function keys: none Shortcut key: none Do you have hand rest: No Waterproof function: does not support waterproof Key technology: mechanical shaft Backlight function: support backlight Whether to support ergonomics: support Line length: 1.5 (meters) Luminous: white Pressure feeling: 45g +/- 20g Style: weak Backlight mode: 3 types Brightness adjustment: 6 levels Suitable for: notebook users; financial, banking and securities workers; counter cash registers; mechanical keyboards without keyboard area colour:White Material:ABS+PBT Size:12.3 x 8.2 x 4.2cm Package Contents: 4 x Digital Mechanical Keypad Only the above package content, other products are not included. Note: Light reflection 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.