The Bally Quick Draw slot machine is an electro-mechanical 20-stop machine with a hold and draw feature. The hold and draw feature was introduced by Bally in 1946 in a small-sized console machine called Draw Bell. Other models followed Draw Bell. Double Up was introduced in 1947. Wild Lemon, Hi-Boy and Reserve Bell were introduced in 1948 and Deluxe Draw Bell was introduced in 1949. There were other models. Quick Draw is a descendant of those machines.
See the Quick Draw in RealPlayer. The ability to hold reels increased the jackpots paid to players. On a 20-stop machine with one Bar on each reel, the odds of a jackpot is 1 in 8000 combinations (20 x 20 x 20). By holding one bar, the odds drop to 1 in 400 for the second try. If two bars align on the payline and are held, the odds become 1 in 20 on the remaining reel. The Quick Draw returned 82.1% to the player.
Quick Draw utililizes a payout hopper rather than a payout tube which increases the sizes of jackpots that can be paid. Bally's introduction of the hopper pay system on the Money Honey machine in 1962 revolutionized slot play in the casinos.