Finally a true noiseless stainless exhaust flapper. This stainless steel carriage assembly houses our newly designed quiet operation flapper. A heavy duty 1/4" pin rotates on precision delrin bushings to insure smooth operation. Fit's in most straight cut 4" exhaust tips. Drilling two mounting holes in your tips is required. We're so confident in the durability of this flapper, it carries a limited lifetime warranty.