The Famus 80mm Wheels with Bearings are ready to roll with bearings and spacers already installed so that you don't have to fight against a strict aluminum core. Although an aluminum core can make getting bearings in and out a little more difficult, it is worth it! The energy transfer feels amazing and it gives a quality roll. Since they come as a set of 4 wheels, they include 8 bearings inside with 4 spacers between them. 

The bearings inside have an ABEC 9 rating, which means that they provide a consistent and speedy roll. Spacers get taken for granted but they really make the roll of an aluminum cored wheel so much more precise.  It is recommended to use a skate tool when ready to change out the bearings (or wheels).