

These flat black rubber gaskets generally fit into a groove or recess in the back of the case and are most commonly used with a threaded case back. Simply measure the inside diameter and outside diameter of the groove the gasket will fit into on the case. Subtract the inside diameter from the outside diameter then divide in half to find the width of the gasket you need to fit your watch case. With 100 different diameters and multiple widths you should be able to find a gasket to fit your watch. These flat gaskets are sold in sets of three to allow watchmakers and others who work on watch case backs to order exactly the flat gasket they need.