The MH-RA40.5 Lens Hood from Pentax is a screw mount metal lens hood specifically designed for the Pentax 01 8.5mm Standard Prime Lens for Q-series cameras. Lens hoods are primarily designed to prevent unwanted light from entering the lens and causing flare. The lens hood also provides a degree of protection for the lens from accidental impact and the elements. The unique design of this lens cap particularly helps to prevent side light from entering the lens. The lens hood comes with its own screw mount metal lens cap.