Decorative Vent Cover for a 24x24 Opening. Resin Paint Grade Grille Can Be Used As Return, Supply, Foundation Vent, Register. Caspian Design. 26x26 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 not flat, there is a 1/4" lip inset (as shown in second photo) 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.