A. The num lock function applies to any other currently connected keyboards. The mechanical switch keypad offers a fast response. B. Compared with other standard keypads, the 21 - key layout has some extensions at the top, including Esc, Tab, Back Space, and FN. C. The mechanical numeric keypad has 3 backlight models and 6 adjustable backlight brightness levels. By simultaneously pressing the FN key and another key, the backlight and brightness can be changed. D. Keyboard Connection: WIRED E. Type: ERGONOMIC F. Interface: bluetooth G. Brightness adjustment: 6 levels H. Backlight mode: 3 types I. Style: weak J. Pressure: 45g +/- 20g K. Luminous: white L. Line length: 1.5 (units not specified) M. Whether to support ergonomics: support N. Backlight function: support backlight O. Key technology: mechanical shaft P. Waterproof function: does not support waterproof Q. Do you have hand rest: No R. Shortcut key: none S. Whether there are multimedia function keys: none T. Connection with computer: wired U. Whether to support plug and play: support V. Number of keys: 21 W. Type: Numeric keyboard X. Applicable models: general Y. Suitable for: notebook users; financial, banking and securities workers; counter cash registers; mechanical keyboards without a keypad area Z. Size: 12.3 x 8.2 x 4.2cm AA. Color: White AB. Material: ABS + PBT AC. Package Contents: 1 x Mechanical Numeric Keypad Only the above package content is included, other products are not. AD. Note: Light reflection and different displays may cause the color of the item to appear a little different from the real thing. The measurement error is allowed to be +/- 1 - 3cm.