The Storm AstroPhysix 15 lb Bowling Ball is a high-performance ten-pin bowling ball designed for medium-heavy lane conditions. Made of reactive resin urethane with an asymmetrical core, this multicolor ball offers great performance on the bowling lane. With a .050 differential and being undrilled, this Storm bowling ball is sure to enhance your game with its polished finish and one-year manufacturer warranty. Perfect for serious bowlers looking to improve their scores, this ball is a premium choice from the United States Bowling Congress (USBC) approved brand, Storm.