The HP 5851-6024 Keyboard Overlay Kit is a replacement overlay for a Japanese-layout control-panel keyboard. HP identifies this part for Japanese KG and KT layouts, helping provide the corresponding key markings on the keyboard.
The kit is listed in HP’s M630 parts information as a replacement keyboard overlay. It is intended for maintaining or replacing the overlay rather than replacing the keyboard itself.
Installation instructions are included to guide fitting the overlay. HP lists the kit as mandatory in the M630 parts table.