Poly-X Core. Blue Stitch Color. Official Ball of USSSA. Yellow ProTac synthetic leather for increased durability. Hot Dot polyurethane maintains compression in hot weather. Worths 12 Classic Plus softballs have blue stitching and are approved for play in the USSSA. Worth Hot Dot softballs are designed to give players consistent hit distance at all temperatures especially true in hot weather conditions. Added to these softballs is the C-LOK adhesive and moisture barrier and then the SYCO composite leather cover for more durability.