Propeller Replacement Propeller Dia (In.) 12 in Bore Dia (In.) 3/4 in Number of Blades 4 Pitch (Deg.) 24 Degrees Blade Material Spark Resistant Cast Aluminum Keyway (In.) 3/16 Number of Set Screws 2 Rotation CW Facing Discharge Required Motor HP 0.25 0.75 Required HP @ Higher RPM 3/4 hp Required HP @ Lower RPM 1/4 hp RPM Low 2 250 RPM RPM High 3 450 RPM Max RPM 2250/3450 CFM @ 0.000-In. SP 1280/1960 CFM @ 0.125-In. SP - CFM @ 0.250-In. SP - CFM @ 0.375-In. SP -