Secondary mirror that I have removed from an 8" f4 GSO reflector. It is in the GSO mirror holder still and I have not disturbed it. I measure the minor axis (reflective coating width) to be 42mm (which confused me a little since it didn't seem to be a standard GSO size?) Maybe 18 mths old and surface looks fine. Also with it is the metal washer that is often found on these GSO holders.