Tire Valve question

[Breakneck]

I have a Linhai 300 that I would like to replace the tire valve stems on.
Reportedly they fail and fail abruptly for some people.

Mine are in good shape right now but I'd like to change them when I want to and not when I have to. I also don't want to chance an accident when it does happen.

My question is I see different sizes of these available on some websites.

How do I know what size to get? Does this really matter?

I can't find anything about this and have searched enough.