American Roulette: In American Roulette, there are two green zero pockets. This means that there is an additional chance that your wagers will be void. It has a payout of 35/1 if you bet on it, but it essentially doubles the likelihood that all bets will lose money.
The 0 (single zero) and the 00 (double zero) are the green slots on the roulette wheel. These pockets could receive a 35:1 payout if hit straight up.