Old Air Products 32-8X - Indash Rectangular Vent / Louver for 2-1/2" Duct Hose Rectanguler Louver can be mounted horizontally or vertically into the dash. Louver features movable veins for multi directional air flow. Overall Size is 5-3/8" X 2-1/8", (Requires a 4-3/4" X 1-15/16" Hole) Fits 2-1/2" ID Duct Hose