THERE ARE MANY VERSIONS OF THESES WATCHES. The Bezel is 39.15mm outside. 30.6mm inside around glass. 34.3mm backside where is attached to the case.The item "NOS Chronosport Chronograph Military Pilot Slide Rule 39.15mm Bezel Lunette" is in sale since Monday, March 4, 2019. This item is in the category "Jewellery & Watches\Watches, Parts & Accessories\Other Watches". The seller is "chronomaticshop" and is located in Vancouver, BC. This item can be shipped to Canada, all countries in Europe, United States, Australia, Japan.