Actually, it was a brilliant idea for the snipers. To my knowledge, it was made by WRA, but I don't know for sure. It was supplied, to be issued with the scope, at the behest of the Horsemen. It is well made, but has no markings on it at all. The lens is held in by a snap ring similar to how the eyepiece is retained in the scope. The information I have does not go into that much detail. One of the photos of A5 scoped rifles, that keeps getting posted lately, has a scope with the attachment installed on the scope.
Jim