The Heliopan 40.5mm Screw-In Rubber Lens Hood prevents unwanted light rays from entering into the lens.It shades the end of the lens and offers added protection to the lens from accidental impactsThis lens hood is made of rubber, which is resistant to UV rays and high temperatureThis hood cannot be separated from the ring as the rubber part is welded to the black anodized brass mounting ringThe grooved interior of this lens hood ensures reduced flare and avoids the unwanted light rays from entering into the lensIt can be converted from normal to wide angle, and it features threads at front for attaching caps and filters