Ten-pin bowling ramp in which a bowler will use two hands and push the ball down the ramp onto the lane. There are three widely recognized delivery styles used while the ball is released onto the lane. (See article: Bowling form.) These are the "stroker", "cranker" and "tweener" styles. Lesser used (and newer) styles include "no-thumb" and "two-handed". Strokers often keep their shoulders square to the foul line and their backswing generally does not go much above parallel to the ground. This type of delivery reduces the ball's rate of revolution, thus decreasing its hook potential and hitting power. Strokers rely on
Ten-pin bowling off center without falling. The pins must show the name and mark of the maker, either "USBC Approved" or "BTBA Approved" and appear uniform. The maximum diameter of the ball is and the circumference of the ball must not be more than , and the ball cannot weigh more than 16 pounds (7.26 kg). Generally, the lightest ball available for use is 6 pounds (2.72 kg). The ball must have a smooth surface over its entire circumference except for holes or indentations used for gripping the ball, holes or indentations made to bring the ball back into compliance with weight-distribution