The International Space Station (ISS) is a joint construction of many countries around the world. Most of whom use the metric system for measuring including sizing of bolts, nuts and fasteners.
The US seems to be stuck on imperial units, while the rest of the world has moved to Metric and anyone who has worked on both an American automobile and one from just about any other place in the world, has found out the nuts and bolts are different. In fact you need to have two sets of tools, one SAE (American) tool set and one Metric tool set.
Are nuts and bolts on the ISS, metric, SAE, or both?