1018 steel with black oxide finish. TE-CO offes a ange of T-slot nuts made fom hadened 1018 steel, fully machined to fit exactly in a specific machine-table T slot. The body is coated with black oxide to pevent coosion due to the use of coolant. Heat-teated steel fo maximum igidity New AC Heat Air Vent Ceiling Roof Plastic Replacement 9L1Z-19893-AG 9L1Z19893AG *The following description does not list all compatible models. HEADLINER CEILING ROOF Ventilation Grille High Performance fl1Z-19893... Compatible for:2011-2014 Navigator Compatible for:2011-2014 Expedition Reference Part Number:BL1Z-19893-AA, BL1Z19893AA Outlet Heater 4X Headline Ceiling Oof AC Heat Ai Vent Fo 11-14 Fod Ac Roof Vent