Here's one to make you go hmmm. Did you know that there are two series of hex nuts? The standard series and heavy series. For a 3/8-16 thread, a standard hex nut is 9/16" across flats and a heavy hex nut is 11/16". Usually the heavy series is used in structural applications and pipe flange connections. Heavy hex nuts are available for all SAE thread series. For me it just means more tools to drag along when doing pipefitter work.
2006 23B Hybrid with 10k round bar WDH
2011 F150 4x4 SCREW Ecoboost, Max Tow, Integrated TBC, 3.73 LS axle, Firestone Ride Rite airbags.