Allnice&reg; Portable Professional Watch Jewelers Crystal Back Case Cover Closing Press Tool Fitting 25 - 40mm DIY Watchmaker Repair Tool Set with 12 Nylon Dies Scratch and mar crystals proof, Straight wall nylon dies. This watch press tool is very useful for closing snap on back watches and installing flat mineral glass crystals. The watch press comes with 12 assorted nylon dies for all size watches and is used to close snap on watch backs, install bezel rings, and make battery changes. Use for diameter 23/25mm, 27/29mm 30/31mm, 32/33mm, 35/37mm, 39/40mm Watch case. It comes with an assortment of 12 dies to allow for 24, 26, 28, 30, 31, 32, 33, 34, 36, 38, 40&42. The press is made of a cast iron metal frame and can be mounted to a bench for stability. The press can be easily operated with one hand.