Propeller Replacement Propeller Dia (In.) 20 in Bore Dia (In.) 5/8 in Number of Blades 3 Pitch (Deg.) 24 Degrees Blade Material Aluminum Keyway (In.) - Rotation CW Facing Discharge Required Motor HP - Required HP @ Higher RPM 1/2 hp Required HP @ Lower RPM 1/6 hp RPM Low 1 140 RPM RPM High 1 725 RPM Max RPM 1725 CFM @ 0.000-In. SP 4414/2917 CFM @ 0.125-In. SP 4225/2611 CFM @ 0.250-In. SP 4016/2008 CFM @ 0.375-In. SP - CFM @ 0.500-In. SP - Blade Height (In.) 4 3/32 in