GWS Slow Fly propellers have a hexagonal style of hub and they are used on gear boxes or brushless motors on a lower voltage or lower Kv Motor they are Slow fly Propellers
2-Blade Propeller GWS Orange Slow Fly
Length 13"
Pitch 9"
Hub Diameter 12.9 mm
Hub thickness 17 MM
Diameter of hole in Hub 3 mm shaped to use a nut 5.6 mm diameter
Colour Orange
Material Nylon
The measurements are approximate