The mini louvers are tooled aluminum and die stamped grilled. No screening. 6 pieces per bag. No. 50000: 1" opening, mill, 3 louver slats provide .18 sq. in. net free area No. 50004: 1" opening, white, 3 louver slats provide .18 sq. in. net free area No. 50001: 2" opening, mill, 6 louver slats provide .47 sq. in. net free area No. 50005: 2" opening, white, 6 louver slats provide .47 sq. in. net free area No. 50002: 3" opening, mill, 11 louver slats provide 1.34 sq. in. net free area No. 50006: 3" opening, white, 11 louver slats provide 1.34 sq. in. net free area No. 50003: 4" opening, mill, 16 louver slats provide 2.88 sq. in. net free area No. 50007: 4" opening, white, 16 louver slats provide 2.88 sq. in. net free area