Bowling ball random when impacting a full rack of pins on the first delivery of a frame, and sometimes when hitting downed "dead wood" pins on subsequent deliveries—the candlepin bowling sport is the only major one that allows fallen pins, provided no part of any fallen pin extends more than 24 inches (61 cm) forward of the head-pin spot, to remain on the lane's pindeck to be used in knocking down more pins with the next ball delivery in the same round—up to three balls are delivered, much as in duckpins, in each round of candlepins for one bowler. Bowling ball A
Five-pin bowling bowlers use a number of terms to denote the results of a throw: All modern bowling centres use automated pin-setting machines (first used in 1957) to reset the pins after each ball is thrown. In five-pin, two types of pinsetters are used—"string" and "free fall". The "string" pinsetter is known for each pin having a string attached to the head. These pinsetters were first invented in 1963 and are characterized by a string being attached to the head of each pin. This type of pinsetter has a low operating cost, so it is the most commonly used type of pinsetter.