The HP RM2-1258-010CN developing gear assembly is a printer service part that drives the developing unit during printing. It helps turn the developing roller as part of the toner transfer process.
The listing names HP LaserJet 4200, 4250, 4300 and 4350 series printers as compatible. This part is intended for maintaining those printer mechanisms when a developing gear assembly needs replacement.
Box contents: developing gear assembly only.