Precision laser cut from 3/8" thick 304 stainless, our header flanges are manufactured in the U.S.A and are machine surfaced. These header flanges are specifically made for the Ford FE 390, 406, 428 low rise port engines, and has the "low rise" ports shuffled to the lower side of the flange. This flange has a rectangle port dimension of 1.500" by 2.000". This flange will fit all Ford FE engines with the standard, low rise, port design.