I seen this set for sale today and I didn't realize that they minted a reverse proof set this year. So I did some research and found out it was a 2 coin half dollar combo for the 50th Apollo 11 anniversary and was a limited edition minting only 100,000 but I found very little information about the metal used to make them. Does anyone know if they are clad or silver? They are selling for $200 for the pair. Thoughts?