The 1966 Special Mint Sets contains one holder of 5 coins including uncirculated versions of the following 1966-dated coins: Cent, Nickel, Dime, Quarter, and Half Dollar. The coins are housed in a hard plastic airtight package. In 1965 Proof Set manufacturing moved from Philadelphia to San Francisco. From 1965-1967 the US Mint did not create a Mint Set or a Proof Set. These are known as Special Mint Sets (SMS).