These incandescent (pre-LED days) lamp covers could be found on a multitude of professional electronic equipment back in the 1970's
RED Plastic lamp cover/lens/bezel
Push and click on - not the threaded type
Dimensions: 9mm outer diameter
7mm inside diameter
8mm depth
There is a small lip inside the cover, this grips the lamp holder and holds the cover in place
These are all NEW OLD STOCK spare parts
Tested as described in the description
This item is not returnable, UNLESS not as described