We have had many calls for larger snap-on nylon dies to fit Part #: CRY-905.00. This set is designed for larger oversized watches that are very popular, and most have snap-on case backs. There are a total of six pieces, three flat on both sides, 35, 40, and 45 mm, and three double sided concave that are 40/42.5, 45/47.5, and 50/52.5 mm concave-shaped.