MBS Stainless Matrix Bearings 

MBS Mountain Board Bearings 12 x 28mm

The MBS Stainless Steel Bearings are exactly what they sound like.... fully stainless steel bearings for the hubs. But what they don't say is that they are a very good grade stainless steel which does greatly extend life compared to standard bearings. These are only really worth worrying about if you are riding a lot on the beach.

Stainless bearings offer improved resistance to rust, and tend to last a lot longer. This is mostly an issue for those riding on beaches or nearby them, where there is more salt. These are not available for Atom boards.

These are only available as 6001 12mm Axle bearings for Channel Truck boards like MBS Matrix and also as 9.5mm Axle size for Vector and Skate Truck Boards.

All MBS hubs fit 28mm bearings except Atom board hubs which take 22mm bearings.
Matrix trucks have 12mm axles.
All Terrain Skate and Vector trucks have 9.5mm axles.