O.S. Front Bearing 21XZ-B

Steel construction
Shielded front (to keep out dirt and prevent fuel leakage)
Open back (to allow oil in fuel to lubricate balls)

One Ball Bearing

Installation into crankcase

Inner Diameter: 7mm
Outer Diameter: 19mm
Thickness: 6mm

This is the bearing that sits in the front portion of the crankcase
which supports the crankshaft.