Ten-pin bowling regulations, identification letters and numbers, and general wear from normal use. For much of the history of bowling, bowling balls were made using a three-piece construction method. Starting in the mid-1990s, however, most manufacturers switched to a two-piece method. In response to these innovative ball designs, the American Bowling Congress placed further restrictions on the technical characteristics of the ball such as the radius of gyration and hooking potential. A game of bowling consists of ten frames. In each frame, the bowler will have two chances to knock down as many pins as possible with their bowling ball. In games
Ten-pin bowling if synthetic. The top of the pin shall have a uniform arc with a radius of . The USBC also has regulations governing the weight distribution of the pin from top-to-bottom. Pins are allowed one or two "voids" (holes) in the belly area (which can be viewed if the pin is cut in half from top-to-bottom). The voids are needed to balance the narrower top half of the pin with the wider bottom half. Without them, the pins would be too bottom-heavy to fall properly when struck. In addition, a standard regulation pin may lean no more than 10 degrees