The U.S. Mint issued Special Mint Sets (SMS) from 1965 to 1967, which are characterized by a better strike than circulation coins but are not proof coins. SMS coins are struck on higher-tonnage presses than circulation coins and have higher-quality finishes than uncirculated coins. However, SMS coins are not usually struck multiple times and are not polished as much as proof coins, so they generally don't match the quality of proof coins.