There needs to be at least 5 selections (legs) to place a 4 Fold.
It consists of individual bets between 4 of the selections for all possible combinations.
At least 4 selections must win to earn a return.
Example
If there are 5 legs selected (A, B, C, D & E):
Bet 1: A x B x C x D
Bet 2: A x B x C x E
Bet 3: B x C x D x E
Bet 4: A x C x D x E
Bet 5: A x B x D x E