This is a GemFan 8x4.5 Reverse Rotation Propeller. GemFan produces high quality propellers for Airplane and Multi-Rotor craft use. The GemFan propellers are available in both normal and reverse rotation as used for multi-rotor craft. These props are made from ABS plastic with a glass fiber fill for extra rigidity and durability.
The 8x4.5 props have a 6mm hole drilled in the front side of the hub, and a 9.5mm hole on the back side of the hub to accept a prop shaft adapter ring. Also included with the prop is a set of six 9.5mm OD adapter rings that step down the center hole of the prop to allow it fit on 3mm, 3.5mm, 4mm, 5mm, 6mm or 8mm motor shafts. If you have a larger threaded shaft on your prop adapter, the center hole can be reamed out to a larger size as needed.