I was looking at steel carabiners when I found this rather interesting set of measurements.
Description Material : Stainless steel - High grade Dimensions: 1 4.5/8 x 7/8 inch (540mm. x 22mm.) Stock : 1.5/8 inch (4mm.) Weight: 0.02lb (0.01Kg.) Features: Heavy duty , Corrosion resistance Working load: 3KN (0.3 Tons)
One and 4.5 eighths is interesting enough, but that equals 540mm in their eyes. What a hoot!