Since 1992 the U.S. Mint has issued special silver proof sets that revived the traditional 90% silver dimes, quarters and half dollars. The 10-coin 2001 and big 14-coin 2007 proof sets each boast seven silver coins. In addition to their precious silver content, these sets are also prized for their low mintages. Respectively, they feature total outputs of just 39% to 51% of the regular clad set's production for those years. Coins were struck by the San Francisco Mint with finest-quality, double-struck engravings and beautiful frosted finishes against dazzling mirror backgrounds.