These 608zz bearings are perfect for your RepRap 3D Printer building project - you'll need 6 for a Prusa Mendel or a Mendel90 and you'll need 2 if you are making a Wade's Extruder. Item: Radial bearings 608ZZ (608Z) 608ZZ Material: Chrome Steel Type: Metal shielded Deep groove ball bearings 608ZZ 608ZZ Closures: Metal Shielded 608ZZ Bearing Size: 8mm x 22mm x 7mm 608Z