The ACME 645 is a precision CNC-machined 4-blade Nibral propeller crafted for ski and wakeboard boats. Featuring a 13.25? diameter and 16? pitch, it combines strong hole-shot, reliable hold, and fuel-efficient cruise-making it a popular choice for heavy-load performance boating.Part: 645Blades: 4Diameter: 13.25″Pitch: 16.00″Cup: .105″Hub Length: 2.75″Bore: 1.125″Rotation: Left-HandMaterial: NibralManufacturing: CNC MachinedMade in USA