"Roger that, I can dent the case back on my gen 1675 with my thumb." The average 1970s 1675 case back is around .9mm thick in the center depending on wear. Just now measured a few repsub etc case backs...one new 'shitinerand' was .9mm, , another was .74mm. An unsigned '21 jewel' sub case back from a guy called 'Cal' 15 or 17 years ago was 1.15mm, this case is built like a Sherman tank with a hole in the case top at 12 with a coil spring and plunger that ratchets against notches machined in the spring wire mounted rotating bezel. These things are Nanuq proof. Maybe. Checked a 10+ year old swisseta 'shitinerand' yacht-molester and it was .84mm. A sapphire crystal Exp II swisseta case from 'River' 12 or 14 years ago was 1.55mm thick. An MBK 'polex' 5513 was 1.75mm, and a DW 5513 was 1.15mm. The case back with the best lettering in the assortment above is the DW. A two year old 5513 case back from Yuki is 1.2mm thick and has the best lettering of the bunch. ...but everyone knows 'shitinerands' are still the absolute best because they are hand made by Elves in the small swiss alps town known as Gelena.