Nylon Derlin Dies Set Replace 4 Watch Case Back Crystal Closer Press Repair Tool This is the replacement die set of 20 nylon dies for the Watch Tool Crystal Press and Case Back Press. The set contain Size of the dies in round shape use both size : 18  20 mm, 21  23 mm, 24  26 mm, 28  30 mm, 31  32 mm, 33  34 mm, 36  38 mm, 40  42 mm, 44 - 46 mm, 48 - 50 mm The set contain Size of the dies in rectangular shape dies : 20mm, 25mm, 30 mm, 35 mm, 40 mm, 45 mm , 2 die on different shape ,2 base dies. The dies are made of high-impact nylon to prevent them from marring or scratching the watch crystal or watch case. They will keep your watch case press working like a charm. 100% New,Never Used Before.