1-27/32 inch width x 1-3/4 inch height Square Port; Mopar V8 Hemi, 426 '64-'71 , 528 '00 1-27/32 x 1-3/4 Square Port, Manifold or Headers, 2/Set Port size needed for stock manifold applications but can be used for header applications as well There are no rubber binders or composite materials in Remflex exhaust gaskets so they will not shrink or harden due to time or temperature eliminating the need to go back and continually retighten your flange bolts Heating and cooling of the exhaust system causes header and manifold flanges to warp resulting in gaps between the head and header which Remflex exhaust gaskets seal completely due to the thickness and compressibility of the 100 percent flexible graphite