The 2012-S Silver American Eagle San Francisco Mint 75th Anniversary Two-Coin set was available in early summer 2012 direct from the U.S. Mint for one month. Sales spiked at the end of the month, right before sales to the public were halted.
During this time, the mint sold 251,302 sets and most of them are now in the hands of individuals. The set includes two Silver American Eagle coins. One is a traditional proof with an "S" mint mark. The other is the only reverse proof Silver Eagle with an "S" mint mark and the third reverse proof Silver Eagle in the entire series.
These coins have been graded by NGC in perfect condition -- Proof 70 and Reverse Proof 70.