The Surfboard Studio Concave Belly Vee 25 inch is an amazing tool for all shapers. It has an easy adjustment so you can make the perfect concave or convex. The tool also comes with 40 and 80 Grit sandpaper. Even if you don't want to use it and hand shape your bottoms and decks at least check you concave, belly bottoms and deck rolls with it to see how good you are.