You must be logged in and verified to contact the designer.
This is for Wade's extruder design. This is the small herringbone gear that fits on the extruder drive stepper motor. Center hole inside diameter 5mm. If your shaft is larger, you will need to carefully, using a drill press, enlarge the hole to the proper size.
Laser-sintered nylon makes for very precise, durable extruder gears. Compare the quality in the photos.