2-1 set up. One center fin, 2 side fins. (bolt is seperate)
Or purchase just a side or center fin individually.
 
Select type (Futures or FCS)
FCS type has two slots that fit into the board, Futures has one long slot.
 
When looking at the board from the bottom (tail) with the fins pointing up (board is upside down) the right side will be the right fin and the left side is the left fin.