USA Signatures is a series of insert sets in 2008 Sweet Spot. The most plentiful version is a white ball with black stitches and red ink used for the signature. The next most plentiful is the Black Glove with Silver Ink. Next is the Red-Blue Stitch version, then the Black Stitch with Silver Ink, and then finally the Brown Glove version. All twenty players are only included Black Stitch-Red Ink version, the other sets are partial parallel sets. The print runs for each card is included in the checklist below. The set includes early autographs of Mike Leake and Stephen Strasburg.