This is the second proof set in the American Gold Eagle bullion coin range, and the first to feature all four denominations (the previous year, only two sizes had proof versions).
The set contains proof versions of the four sizes of American Gold Eagle bullion coins issued in 1988 - a full ounce struck by the West Point Mint, with a W mint mark, and three fractions (half, quarter, and tenth-ounce) struck by the Philadelphia Mint with a P mint mark - unlike the respective bullion coins, which were also struck by the Philadelphia Mint but without a mint mark.
The set comes in a booklet-styled folder with a Certificate of Authenticity. Mintage is unknown, and the mintage of the coins in the sets is presumably included in the reported proof mintages for the year. | 
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