If you need to replace your damaged case tube for you watch you need to measure the size of the old one. Use this guide to learn how to measure a watch case tube.
Once the old case tube is free of the watch case, lay it out in front of you on your work bench. You will start by taking your digital gauge and using it to measure the outside diameter of the case shoulder. Open the jaws of the digital gauge wider than the size of the tube and position the jaws on either side of the tube. Then close the jaws until they rest snugly against the edges of the tube.
Record the measurement.
Once you have all three measurements in hand you are ready to order your new watch case tube. Head over to Esslinger.com to find the right case tube and order online!