This is not the ordinary mold most of us have used. There are 24 individual ribs that can be arranged to meet your needs. There are two different profiles, straight and concave, that fit the same base. The top ring holds the ribs securely in place and is easily removed to change the mold's configuration. The stainless steel fins detach from an aluminum base. No nuts, bolts, or screws. Can be easily changed. 9-1/4'' base to top ring. Just like the curved design, all fins are interchangeable with the mold base.