standards that they use for these drop in valves/cartridges? I need the cold side, I bought one off of amazon that EVERYTHING is the exact measurements (using my calipers) EXCEPT the thread pitch was different. Not only did it seem that the pitch wasnt as fine, but slightly larger diameter, by 1-2mm. The one I bought says it is G 1/2" thread pitch. I have NO idea what that means or the other standards that are used, and searching the internet seems to just make it more confusing.

Here is the only I bought. Like I mentioned, all other measurements are perfect, EXCEPT the threads. I've searched like crazy and don't really understand how the pitch works on plumbing and what mine might be called. Anyone with some knowledge have any insight?