This is for mechanical keyboards that support hot swapping of Cherry Mx key switches - for example the Planck EZ that I'm typing this on.

If you have developed a custom layout (or adopted one) that works best with fewer than even the default 47 keys on a 40% board - and it happens..! - then you need a way to neatly blank off the open hole in the keyboard plate.

This blank simply push fits into that hole and is held in by friction - nothing fancy