Seat Foam - High density - 25mm, 50mm, 100mmThis high density foam offers the ideal firmness for motorcycle seats and can be effortlessly shaped using sandpaper or a flapper disk on a grinder. It cuts smoothly with a sharp knife and even more quickly with an electric kitchen carving knife. Shaping a seat is a highly rewarding process and is one of my favorite aspects of building a motorcycle. The foam is 700mm X 300mm or (27. 65" X 11. 81") Choose from 3 thicknesses: 25mm, 50mm, and 100mm. (0.