APC Slow Flyer Electric 7x4 Prop
APC Slow-Fly Electric Series props offer high thrust at low RPM, and offer great value for your electric powered models. The center hole of the prop is designed to accept a reducing bushing to fit your propeller shaft. Included with the prop are 2 bushings to fit 5mm (3/16") and 6mm prop shafts.
According to the widely accepted Maximum RPM formula of 65,000/D for APC SF-Series props, the 7x4SF prop should not be used over 9,286 RPM.