Small Block Ford big tube wide rectangular shaped port header adapter exhaust flanges. These flanges come as a pair and are designed for 2" horizontal centerline bolt pattern SBF heads, machine work included. Includes (8) countersunk holes for bolting 3/8" diameter flat head bolts to head and (8) 3/8"-16 tapped holes to locate SBF flanges with larger port sizes for 1-7/8" or 2" diameter primaries. SBF header flanges not included, laser-cut from heavy-duty 3/8" thick carbon steel for superior resistance to warping from high heat, recommended header flanges are HFSBFTFHP188 or HFSBFTFHP200, or any other 3/8" thick Small Block Ford header flange with 2-3/4" width diagonal header bolt pattern.