Kindly Reminder: Please calibrate the E-steps from 100 to 139 Lubricate the gears before use for better results Stepper motor is ONLY for reference,NOT included in package What are the advantages and upgrades of the REDREX dual gear extruder ? Issues that this fixes: Miss-aligned Extrusion feed gears Excessive part damage from wear Missing layer extrusion Over and under extrusion Bowden tube failure Filament damage and grinding Jammed nozles Retraction errors Metal fragments enter the hot-end Squeeking and rattling noise Low-quality prints Broken filament Hogging of filament Ender 3 V2 / Ender 3 V2 Neo / Ender 3 Pro / Ender 3 / Ender 3 Neo / Ender 5 Pro / Ender 5 Plus / CR10 S / CR10 V2 / CR10 Max / CR5 Pro / CR5 S CR-3040 Pro Reminder: I. for 3d printers with filament detector,as the height of our dual gear extruder may be different from the original one, please print the model to rise up the filament detector to make them at the same height; II. for Vyper users,please calibrate the e-step from 385 to 139 and swap the motor wire sequence to make it turn forward instead of reverse III.for other brand 3d printer users,you may need to print the fan shroud yourself"