sampaio: Best to email Acer yourself with that enquiry. They can do different bearing kit configuations I think.
I use the ceramic nitride set (except in the rear upright) in my 415MSX. They are great, not too badly priced compared to other bearing companies, and the advantage being an overseas person is fast, free postage. I got my bearings within a week, from the US to Australia.
I would highly recommend them to anyone wanting to upgrade from their kit bearings, especially if you live overseas.