This precision made hobbed gears are designed to be attached directly to a stepper motor with a 5mm shaft or 8mm for Bowden Extruder.
These hobbed gears grip filament strongly, that is better than any gear bolt.
Please note if using direct drive that you do need a fairly “powerful stepper motor”. Otherwise in our opinion using Bowden Extruder is well operated.
Material: Stainless Steel
Bore Diameter: 5mm or 8mm
Outer Diameter: 12.5mm
Hobbed Diameter: ~10.5mm