The side edges of a bodyboard are called the rails. The rails are angled at the top and bottom, resulting in a point on the edge of the board. You’ll see this angle listed as a ratio in the specifications for the bodyboard. A 60/40 ratio on the rails refers to a lower edge that’s slightly larger than the upper edge. A bodyboard with a 60/40 rail is easier to grip and control, but it won’t move as fast as a 40/60 ratio bodyboard rail.