GWS Direct Drive 10x6 Propeller GWS Direct Drive series props offer high efficiency and great value for your electric powered models. The center hole of the prop is designed for a 3mm shaft, and can be drilled out for a 1/8" (3.17mm), 4mm or 5mm shaft. According to the widely accepted Maximum RPM formula of 100,000/D for GWS DD series props, the 10x6 DD prop should not be used over 10,000 RPM.