ET-60 Lens Hood is a device used on the end of a lens to block the sun or other light source in order to prevent glare and lens

ET-60 Lens Hood for CANON Lens, they offer some level of protection for the lens due to the hood extending farther than the lens itself

It's for:
EF-S 55-250mm f/4-5.6 IS
EF 75-300mm f/4-5.6
EF 75-300mm f/4-5.6 II USM
EF 75-300mm f/4-5.6 II
EF 75-300mm f/4-5.6 III USM
EF 75-300mm f/4-5.6 III
EF 90-300mm f/4.5-5.6 USM
EF 90-300mm f/4.5-5.6 for CANON Lens