The ES-52 Lens Hood from Canon is designed to fit the Canon 40mm EF f/2.8mm STM Lens. Lens hoods offer protection from unwanted light entering your lens and causing glare, especially when shooting toward your light source. They also offer a degree of physical protection for your lens against accidental bumps. ;The ES-52 is a screw-on type lens hood specifically made to fit the Canon EF 40mm f/2.8 STM lens.