Ask the seller if he is including the hub. That's the beauty of props like these, you can change the prop and use the same hub. Maybe he changed to a different pitch or diameter and is using the original hub.
Quicksilver HUB ASSY.KIT MERC 835257Q1
Not sure if you need the below with a 19" pitch, but just in case.
Use Flo-Torq IV hub kit (#835257K10) to reduce clutch rattle on 90/115 HP Command Thrust (CT), 135-200 HP 4 cylinder Verado and 150 FourStroke. Clutch rattle may be present when using 18P or lower stainless steel propellers.