ball, two defensive halfbacks are used instead of one strong safety in the American game. The ball The sizes of individual American and Canadian footballs can vary within specified size limitations. Despite the CFL and NFL having different specifications until 2018, they overlapped to a sufficient degree that from at least 1985 forward, the same ball could fall within the requirements of both leagues. Historically the CFL ball was slightly larger, both because of slightly bigger specifications, but also because CFL manufacturers tended to make balls at the larger end of the allowed tolerances as opposed to NFL manufacturers, which built balls to the smaller end. However, the CFL has updated its specifications twice—first in 1985, and most recently in 2018. The latter change saw the league adopt the NFL's specifications. Before it adopted NFL standards, the CFL's regulation football size was specified as short circumference from ; long circumference from . The regulation size for an NFL football is specified as short circumference from ; long circumference from . Despite the fact that before 2018, the CFL rules allowed for a smaller legal ball and the NFL rules allowed for a larger legal ball, a common misconception existed among media, fans, and even players that the then-current CFL ball was bigger. Some professional quarterbacks stated that they noticed a difference in size. Another difference between NFL and CFL balls is that Canadian balls have two complete white stripes around the football from the largest diameter of the ball and NFL balls have no stripes at all. The CFL retained its striping scheme when it adopted NFL measurement specifications in 2018. College football and high school football both specify the use of stripes, but only on two of the football's four panels (the ones adjacent to the laces). The original reason for adopting striped balls was to make them easier to see at night in an era when stadium lighting standards were far less rigorous compared to today - historically, CFL teams played twice weekly, which meant they routinely played on weeknights. Number of downs In American football, a team has four downs to advance the ball 10 yards, while in Canadian football the limit is three downs. Scrimmage In both games, the ball is placed at a line of scrimmage, in which a player known as the "centre" or "center" performs a "snap" to start a football play. In