In a Heinz bet at least two selections must be successful to get a return. The trebles, four-folds, five-folds and six-fold mean that if you get more than two winners your returns begin to jump in big increments as more of the multiple bets win. It's most often used in horse racing betting.
The heinz flag bet is a 6 selection wager consisting of 87 bets: 15 doubles, 20 trebles, 15 four-folds, 6 five-folds, 1 six-fold and 15 Up-And-Down SSA Pairs.