40mm. Circa 1987. The Rolex Explorer II was first released in 1971. It has carried on for 46 years as a robust and functional extension of the original Explorer family. The 40mm stainless steel case features a 24 scale bezel for use as a second time zone function. The screw down crown and case back ensure water resistance to 100 meters. In the words of Rolex - The Explorer II swiftly became the watch of choice of speleologists, volcanologists and polar and jungle explorers, thanks to its' specially designed features. Personally, I am not acquainted with anyone who falls into one of these very specific groups, but for everyday adventures and travels, this watch is the perfect companion. This watch is presented on the Jubilee bracelet that came with it at the time of the original purchase. At that time it wasn't uncommon for authorized dealers to swap the Oyster for the Jubilee bracelets upon the request of a customer. Original guarantee and booklet are included.