If you're going to choose a single fin, this is your basic, your classic long board single fin. This is the fin that they used in the '60s. This is what started out surfboards. This is what was on boards when they very first started out. It's in the center of the board, in the back of the board, and what it is, it's the rudder, it's what's steering you. It's about seven and a half inches tall and it's got a long base. What that does, it gives you a long, driving turn. It's not going to be a real sharp turn. It's going to be a long, gradual turn along the face of the wave. The single fin is, it's a compound curve, which means it's curved on both sides. And what the curve does, the water will hug around a curve surface. So the water will flow down the bottom of the board. And because the single fin is curved surfaces on both sides, it's foiled on both sides, so the water is curving around this fin and holding the board down in the water. And that's a single fin.