Material: Typically made of cast iron or steel
Mounting type: Bolt-on
Number of mounting bolts: 6 or 8, depending on the specific model and application
Fan mounting type: Typically a bolt-on hub that attaches to the fan blade assembly
Belt pulley mounting type: Typically a press-fit pulley that attaches to the fan support hub
Finish: Typically painted or coated to protect against corrosion