Propeller, Replacement, Propeller Dia. (In.) 18 in, Bore Dia. (In.) 5/8 in, Number of Blades 4, Pitch (Deg.) 23 Degrees , Blade Material Spark Cast Aluminum, Keyway (In.) 3/16 in W and 3/32 in D, Number of Set Screws 2, Rotation CW Facing Discharge, Required Motor HP 1/3, Required HP @ Higher RPM -, RPM Low -, RPM High -, Max. RPM 1725, CFM @ 0.000-In. SP 3410, CFM @ 0.125-In. SP 2920, CFM @ 0.250-In. SP 2410, CFM @ 0.375-In. SP 1,980 cfm, CFM @ 0.500-In. SP 1,525 cfm