at my shop i have 6 boxes of basically every bearing, what i have found with FSA bearings is that quite often you really need to fit the FSA bearing, they seem to do weird things where everyones standard diameter might be 41.8, but FSA is 41.7mm there are some very tiny differences, it might be done to force you into buying specifically their bearings but either way it can be annoying
when i'm replacing bearings i get out my digital measuring weapon, measure the outside diameter, the inside diameter, and width, then i go to one of my boxes and find the appropriate bearing, it's rare to not have the right one, unless it's FSA where i get caught out, but i've started building a box specific to FSA and the rep is getting me the details of the top 10 most common bearings so hopefully i'll soon have a good spread in stock.
i'm happy to post some out if you're struggling. i'm in the new forest, 02380 890712, back in on tuesday
this pic is from a couple of years ago, i have 3 more boxes like this now