P2 Specular Silver with Flange with 1-1/2" x 1-1/2" cells x 1" thick. Maximum outside dimensions of flange are 22-1/2" x 46-1/2" Minimum outside dimension is 21-1/4" x 45-3/8" Measure your existing lens or existing lighting frame to find out what size to choose from the drop down lists. ***NOTE: These parabolic lenses are not designed to fit directly in a ceiling grid system.