Choosing your right rail is a pretty important thing because the rail line is what you're compressing on in when you're doing your turn. So, if you're a bigger guy, you're going to want a fuller rail, a fuller rail meaning a thicker rail, so that way it carries your weight through that turn and gives you enough speed coming out of that turn. Because otherwise, if a bigger surfer was to get a thin rail, what happens is he'll compress into that turn and want to come out of that turn, but because there's not enough volume in that rail line, it doesn't pick him up and project him out of that turn. With a fuller rail line, you have a flat deck, bringing the volume out to the rails, and the lightweight guy, or the more sensitive rail line will be a dome deck, it'll be curved down into, tapered down into a thinner rail line. Now, with the rails going up to the nose, usually it's thicker in the center where you're paddling, and then the rail line will become thinner up in the nose. And then, also, the other way, down in the tail, it will become thinner, down into tail to make it more sensitive when you turn. And that is rails.