Some years ago I bought one small cute diopter for my 98 Mauser. The seller told that it was taken away from an older military rifle. I have tried to find any futher information of mine diopter but without any luck. Does anybody here know where it comes from ?

As you see, there is three screws to adjust for lateral and vertical but without any scale. This diopter has been designed for attaching it to actions back bridge with two screws. The vertical adjusting screw need one more hole to drill.