I've got a great shower head here in China, and want to bring it back to the US with me. The threading looks about the same, just eyeballing it. Does anyone know if this is something that has an international standard?
British Standard Pipe is a family of standard screw thread types that has been adopted internationally.
At least 41 thread sizes have been defined, ranging from 1⁄16 to 18, although of these only 15 are included in ISO 7 and 24 in ISO 228
ISO is, of course, the International Standards Organisation.
However I'd not be surprised if China, and most of the planet, use metric threads for this sort of plumbing.
The US has a proud, some might say stubborn, habit of ignoring International standards and inventing its own.
The standard thread size for modern-day shower heads in the United States is 1/2-inch NPT.
That's National Pipe Thread. Not BSP, Not metric.
In your shoes I'd measure at least the internal diameter and thread pitch. I'd also check for straight vs tapered.