The Ee-D grid-type focusing screen maximizes viewfinder brightness & is optimized for use with f/5.6 EF lenses & slower. It provides a 3-line (horizontal) by 6-line (vertical) grid for easier composition & horizon alignment. Camera Focusing Screen 3-line (horizontal) by 6-line (vertical) grid Optimized for use with f/5.6 EF lenses Genuine Canon Accessory