25 years after designing the thruster, Simon Anderson is producing quads.  These fins are for his small wave quad boards.  Both the front and rear fins have proportionally the same outline resulting in superior handling, speed and control.  The Medium template will suit small to medium surfers while the Large template will cater for larger surfers.

To determine the fin you need, stand at the back of the board with the fins pointing UP.  Now - do you need the fin on the Left, the Right, or the Center?