There are several variations of the “en prison” rule that also affect the house edge. In Atlantic City all even money bets follow a variation of this rule. In the event the ball lands in 0 or 00 the player will lose only half of any even money bet. This lowers the house edge to 2.63% on these bets. This rule does not apply on single zero wheels. On single zero roulette tables using the European “en prison” rule the house edge drops to somewhere between 1.35% and 1.39% for even money bets depending on the variation of the rule. This rule does not affect non even money bets. Single zero roulette wheels can be commonly found online and outside of the United State. The odds for a single number changes from 1/38 to 1/37 on single zero tables. This drops the house edge to 2.70%. In standard U.S. casinos these tables are generally only found in high roller rooms