The Quad Fin layout consists of 2 front fins and 2 smaller quad rear fins. It pretty much blends attributes of the twin fin and the thruster. That added down-the-line speed without the resistance/drag of the center fin in a thruster, but with more hold and controlled maneuverability than the twin.
On smaller gutless days, having a quad with the rear fins closer to the rail and slightly further up, will really loosen the board up for you. This allows for quick maneuvers and sliding the tail around as you need with ease. It also gives you that much more speed through the flats as there is no resistance of a trailing center fin.
For the bigger, hollow days, the quads with rears place back a little and also close to the rail will provide extra speed and hold in the face of the wave. You can take higher lines on steeper waves with the extra hold of having two fins on the rail. Plus that extra speed, again due to no center fin drag, comes in handy on those fright train barreling waves where there is not much room to turn anyways.
Read our Surfboard Fins Guide, chat live, or leave an enquiry for advice on choosing the right surfboard fins.