Compatible OPC drum haven't a metal gear. This gear should be remove from the original OPC drum with help a flat screwdriver and it uses in compatible OPC drum.
Also searched as:
Hewlett Packard (HP) LaserJet Pro 400 M 425,M425, LJ M425, Laser Jet M425, Laser JetM425,
ProM425, LJ ProM425, Laser Jet ProM425, Laser JetProM425,
HPLJPro400