Plastic air outlet grills Plastic air outlet grills A. PN RD-75 75MM duct size high temp plastic air grill. 4" mount flange, open/close rotating louvers. B. PN 06-2019-3 3" duct size low temp plastic air grill. 4" mount flange, rotating fixed air vane. C. PN 3840BK 4" duct size low temp plastic air ...