3" tall x 2 1/4 wide. Just needs a little polishing to restore it to original condition. No idea of the who or when. The marks for the switch choices are M, O or V. Markings that can be made out on the opposite side are; 7'5cm M32 (possibly it is a 2 but smeared so cant say for sure) next marks are also kind of smeared but may be M32 38. Any information? Thankyou.