Genuine Canon filter ring retaining screw for the EF 50 1.2 L USM lenses. Also used as the lens stopper screw for the EF 16-35 2.8 L USM, EF 16-35 2.8 L II USM, and EF 17-35 2.8 L USM, and over 60 other Canon lenses. Package of 1 screw. Made by Canon Japan.