Ok I got the case back from Athaya with the OPB engraving and a Nightwatch case back without engraving. Both of them are the thicker version meant for the 6152/1. Nightwatch has a thinner version that he sells and he has it listed as a 372 case back. That one is thinner and as a result probably not as solid feeling as the thicker one. Having both the Nightwatch and Athaya case backs in my hand they both feel solid. After installing both, the thicker size compared to the display back is not noticeable. I am on the same strap hole with the solid case back as with the thinner rep display case back. Although both the Nightwatch and Athaya case backs are solidly built I am keeping the Athaya case back on the 372 because of the OPB engraving. It is highly polished, great quality and looks great on the watch. Anyway, on to the pics!