The athlete must rely on the ball. For fast pitches, skilled fielding, and accurate throws, the THUNDER HEAT® Fastpitch Softball is the trusted ball for the dedicated athlete. 12" Non-Association Fastpitch Softball Center: Poly Precision blended cross-linked polyurethane system High density and maximum resiliency Ultra-thin ZN Composite cover to get to the core faster Seams: Raised COR: 0.47 Compression: 375 lbs. Meets all Fastpitch Association Specs.