700a – two piece louver with inverted split y blades two rows of inverted split y blades louver with two-piece thru-bolt design for wood or metal doors material: 18 gauge crs frame and blades. Min size 6 x 4, max 48 x 80. Multiple sections can be combined for larger sizes. construction: louvers & frame: 2 rows of inverted split y blades at 1 intervals are attached by interlocking construction to the 3/4 deep welded frame. 1-1/4 trim, with mitered and welded corners and countersunk mounting holes. Non-vision construction. Louver frame is screwed into door from 2 sides.