Tooled aluminum; die stamped grill. No screening. 6-pieces per bag. No. 50000: Mill, 1'' opening, each vent has 3 louver slats No. 50004: White, 1'' opening, each vent has 3 louver slats No. 50001: Mill, 2'' opening, each vent has 6 louver slats No. 50005: White, 2'' opening, each vent has 6 louver slats No. 50002: Mill, 3'' opening, each vent has 11 louver slats No. 50006: White, 3'' opening, each vent has 11 louver slats No. 50003: Mill, 4'' opening, each vent has 16 louver slats No. 50007: White, 4'' opening, each vent has 16 louver slats