Patented Thunder Heat™ technology makes these softballs perfect for use in all weather conditions because it is less susceptible to compression changes caused by temperature changes. The 12" ball is constructed from a high-density precision blended cross-linked polyurethane center that is held together with a unique gluing process. Bonding the durable, yellow leather cover to the core makes the ball resilient and gives pitchers a true feel. The ball has a .47 COR rating and 375 lb of compression and is certified to use in all USSSA competitions. Sold in a dozen.