Bowling ball Bowling ball A bowling ball is a piece of sporting equipment used to hit bowling pins in the sport of bowling. Balls used in ten-pin bowling are typically hard spheres with three holes drilled in them, one each for the ring and middle fingers, and one for the thumb. Regulating bodies such as the USBC maintain requirements for the properties of bowling balls, including size, hardness, and number of holes, as well as maintaining a list of bowling balls approved for competitive play. Other bowling balls, such as those used in five-pin bowling, candlepin bowling, and duckpin bowling are smaller,
Bowling ball diameter in the range of to . The surface of the ball is required to include markings to indicate the manufacturer's brand name, the name of the ball, the center of gravity (before drilling), the orientation of the core (the Pin), and the axes of the high and/or low radius of gyration (as applicable). Additionally, markings must include an individual serial number and the logo of the USBC. Holes are allowed to be drilled into a bowling ball for a variety of reasons, and bowlers must be able to demonstrate that such holes can be used as claimed. Up to