Replacement Propeller Hubless Propeller Dia (In.) 18 in Bore Dia (In.) - CFM @ 0.000-In. SP 2 411 cfm CFM @ 0.300-In. SP 1 665 cfm Min HP 1/4 hp Max RPM 1 140 RPM Pitch (Deg.) 23 Degrees CCW Rotation Number of Blades 4 Propeller Material Aluminum Galvalume Spiders For Use With Air Conditioning Condensers Heat Exchangers and Unit Heaters Heat Pumps Requires Interchangeable Hex Hub 2A563 or 2A564 or 2A565