How do you know what size die you need to open your Rolex®, Omega®, or Breitling® watch? Because there isn’t a reference chart for case back sizes and dies you have to measure the distance yourself on your watch back.
Measure the distance of one of the opening “dots” to one on the other side of the case back. Since there are only 5 “dots” they are not directly across from each other. You can measure the distance between them from more than one “dot” to get a more accurate dimension.
Breitling® & Panerai® Watches
Measure the distance of one of the flat sides to on the other side of the case back. Since there are an odd number of sides they are not directly across from each other. You can measure the distance between sides from more than one angle to get a more accurate measurement.
Rolex® & Baume Mercier® Watches
Once you know what size you need, head to Esslinger.com to find the right case opening die. You may need to round your measurement up or down a little to get the closest fitting die for your watch.