While many things are different between Europe and the US, the difference between microphone stands can be vexing for the traveling musician. While the US uses 5/8" threads for mic stand accessories, they use 3/8" in the EU.
This little adapter solves the problem by adapting 3/8" stands to accept 5/8" stand accessories (i.e. mic clips & shock mounts). Get a couple and throw them into your gig bag, so you'll have them when you need them.