Twizzy: Shortboard Thrusters are called 'thrusters' because they give 'thrust' off the bottom. On a 2+1 performance Longboard the outer fins are called 'Side Bites'. In other words they 'bite' and add THRUST to come not only UP but also OUT off the bottom and can PUMP the wall like a Thruster shortboard. (Unless you name is Tudor don't try to LAY a single fin out on just a few feet of rail.)