Rollin' rollin' rollin', you can now roll around smooth as silk with these radial bearings. Often referred to as "skate bearings" They're good for supporting a rotating rod or as a wheel hub. However, these are higher quality, meant for continuous use so they'll last longer than cheap skateboard bearings. Ideal for use in your CNC project or robot. 
Standard 608ZZ sizing, which means they're 22mm outer diameter, 8mm inner diameter, and 7mm wide. They're pre-greased and shielded so they wont get clogged easily. 11.5 grams per. Comes in a set of 4! 

Radial Ball Bearing 608ZZ - Set of 4 (2:44)