Axial fan impellers. New old stock from the Amtrak Superliner project, to be used as ceiling fans. I was going to build a wind tunnel with them. Life intervened. Blading has sophisticated airfoil shape; each blade is removable and replaceable. One keyway with two setscrews in hub. Would be ideal for a row of dairy barn ventilators ... or ...? Price is for one fan impeller. I have 10 for sale.