The Flatso is so flat, a little fat, and crazy fast. When the waves are kinda fat and flat you need a board to match. It has a deep single concave bottom and should be ordered 4"-6" shorter than you regular shortboard and about an inch wider. It's designed to be a twin-fin, but I suggest getting the trailing fin box (2+1 setup) to have a mini-trailer option. four and five fins are available too.