MASTER AIRSCREW 9 X 4 PROP GF SERIESPerformance Propellers for Model Airplanes - GF Series FB - factory balanced propeller - for more information click here GF Series is specially designed for sport flying and high performance model R/C airplanes with electric motors or glow engines. Made of Glass Fiber Reinforced Composite for strength & durability. Propeller diameter 9" / 229mm Propeller pitch 4" / 102mm Hub thickness 7/16" / 11.1mm Shaft diameter 1/4" - 5/16" / 6.35mm - 7.94mm * Propeller Weight 0.51oz / 14.5g Direction of rotation Normal / Tractor Material Glass Fiber R Composite Color Black