This short lens hood is smaller than the hood thats included with the EF 400mm f/2.8L IS III USM for easier handling and transportation. It prevents stray light from entering the lens which can be a source of flare and ghosting whilst providing a degree of protection for the lens front element. Its built to the same exacting standards as the EF 400mm f/2.8L IS III USM lens, designed to blend in perfectly with its thermally-insulating white paint exterior. Benefits Prevents flare and ghosting when shooting into the light Shorter design is easier to handle, transport and store Protects the lens front element from accidental damage Designed specifically for the EF 400mm f/2.8L IS III USM Styled to match the white exterior of Canons super-telephoto lenses Lightweight so wont add weight to your lens Can be reversed and attached to the lens to save space What\'s in the box Short Lens Hood ET-155B Compatibility EF 400mm f/2.8L IS II USM EF 400mm f/2.8L IS III USM RF 400mm F2.8L IS USM RF 800mm F5.6L IS USM