This V-Groove Drive Pulley is recommended as an OEM Replacement only. It does not have a hub attached. The inside diameter is Splined. This pulley does not have a keyway. There are no set screw holes. This part is Zinc-coated for long-term rust prevention. Additional Features: Made of Steel Works with 4L/A belts Splined bore; heavy duty split steel Direct OEM Replacement for: Hustler Big Dog: 603987