Decorative Vent Cover for a 16x12 Opening. Resin Paint Grade Grille Can Be Used As Return, Supply, Foundation Vent, Register. Heritage Decorative Design. 18x14 Overall Size Important: Main picture shown is a 12x6 grille (overall size approx. 14x8). Choose size based on your opening. The back of the grille is flat and will go over your opening, not in it. See second photo for back of grille. Grille is unfinished polyurethane material and will need to be painted by you Grille will come with predrilled countersunk screw holes and screws Grilles are for wall or ceiling use only. Not for floor use.