This is the newest waterproof tester available from Bergeon and it tests up to 10ATM. Using this tester, you will be able to detect any leaks on a watch case. Simply fill the tank with water (distilled is preferred), place one or two watches on the hanger, then seal the jar. Now you jut raise the pressure inside the jar to the preferred ATM by using the pump handle. Now when you lower the watches into the water, you can detect any leaks by noticing any bubbles that are escaping the watch. You can test the water resistance from 0 – 10ATM.