While most modern automobiles have been metricized, strangely enough through-hole electronics are still built around 1/10th inch spacing (which is often referred to as 2.54 mm).

Granted, through-hole technology is used primarily by hobbyists in this day of age, but it’s still hilarious how perf board, DIP headers, dupont wires and most other things are still built around 1/10th inch spacing.