This is an easy question to answer. Let me take a bit of effort to answer it:
Yoyo bearings(or rather, bearings used in yoyos) tend to come in sizes that due to widespread acceptance, can be considered standardized sizes. It’s not a “one size fits all” though.
To consider replacement bearings, you need to know what the size of the bearing the yoyo uses for the yoyo you wish to replace the bearing in.
To the best of my knowledge, One Drop yoyos use a Size C bearing.
Most YoYoJam yoyos also use a Size C bearing, as well as most YYF yoyos.
All CLYW yoys also use a C-sized bearing except for the small bearing Bassalope.
You can see that the C-bearing is one of the more popular bearing sizes.
Check your yoyo’s specs. It will tell you what bearing you have, as well as what size bearing to get.
So, let’s say you want that shiny new CBC Gold 10-Ball CenterTrac. It is a C-sized bearing.
Let’s say you want to know if it will fit inside your Dark Magic II or Duncan Raptor or YYF dv888. Good news: these all use a C-size bearing. However, if you had a Duncan Freehand Zero, it won’t work because that yoyo uses an A-sized bearing. The H-spin Beysick uses a D-sized bearing, so it wouldn’t work there either.
Any C-sized bearing will fit in any yoyo that uses a C-sized bearing. That means you can choose ANY C-sized bearing as a replacement, be it a CBC brand bearing(in a C-sized, they also make an A-sized centertrac), One Drop 10-Ball, General Yo, Terrapin X(make sure it’s C-sized, he does other sizes as well), Trifecta, Crucial Grooved, YYJ Speed, Dif-E-Yo KonKave and plenty of others.
The ad for the bearing states what size the bearing is. If it’s a C-sized bearing, it will fit any yoyo that uses a C-Sized bearing. It’s up to the purchaser to know what yoyo to put the bearing in.
I keep track of the specs for my yoyos in a database, so that way if I should need to replace a bearing, I’ll know exactly what size to get. Most people should do something like this at least for inventory purposes: make/model/response pad and options and bearing size as a minimum. I track a lot of other information too such as colorways, surface treatment(s), axle technology and more so if anything ever has a problem, I have information readily available.
And no, this is not a dumb question.
Note: The Euro-C bearing is NOT the same dimensions. I think it’s a little bit smaller.