These go through an initial hot chemical wash and then are inspected for any pitting or corrosion. Bearing radial and axial play is checked and rollers are discarded if out of specification. Passed units then have all wear surfaces re-ground to factory like new condition. Units are thoroughly cleaned in a solvent solution and bearings are re-oiled with assembly lubricant. They are then sealed in an air-tight package so they are ready to install in your cylinder head. Price includes set of (8) followers.