Ten-pin bowling over the Model A), all three versions are still in widespread use. The television age of the 1950s also helped to increase the popularity of ten-pin bowling, as images of the sport began to enter the homes of millions across the United States. Nationally televised programs like "Jackpot Bowling" and "Make That Spare" became popular on Friday nights from the late 1950s into the early 1960s. Following many years of debate over what constituted a professional bowler versus an amateur, Eddie Elias founded the Professional Bowlers Association (PBA) in 1958. The PBA's "Pro Bowlers Tour" became a permanent part of
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