A medication injection pen, including a housing, a push button, a dose set knob (DSK) including at least one internal tooth and a ring of DSK ratchet teeth, a driver including at least one external tooth and a ring of driver ratchet teeth, a clicker operatively engaged between said dose set knob and said driver having at least a DSK ratchet arm and at least a driver ratchet arm, wherein said driver is prevented from rotating with said dose set knob while moving axially with said dose set knob during dose setting and dose correcting, and when said push button is depressed, said clicker pushes said driver distally such that said at least one external tooth of said driver engages said at least one internal tooth of said dose set knob thereby forcing said driver to rotate with said dose set knob during an injection.
