Boca Bearings will they fit?

[Moysays]

Does anyone use them? Boca's webiste has many sealed bearing sizes to choose from, but I don't know size/s to get. The guy at the bike shop never heard of them ,and said my hubs wont accept sealed bearings. I'm looking for a second opinion here.
My bike is a 1997 RockHopper.

[DaveM]

I'm not sure about your particular bike, but generally you can't put sealed bearings into a hub made for loose bearings. The hub and axle parts need to be made specficially to hold the sealed bearing.