The lens hood can assist in keeping moisture or wind-blown debris off the lens Twist-lock mounting for extra security, can be attached in the opposite direction for storage Prevent glare and lens flare caused by unwanted light Smooth surface Designed for Canon EF 75-300mm f/4.0-5.6 USM, II, II USM, III & III USM Lenses, Canon EF-S 55-250mm IS Lens