Stage 8 8906 Locking Header Bolt Kit with 8mm Bolts for Ford 4.6 and 5.4 Liter Modular Engine Grade 8 bolts will not stretch when hot Duplex nickel finish for a superior look and corrosion resistance Double hex head includes 3/16 inches recessed allen head for easy installation Removable and reusable Can visually inspect; no need to put a wrench on to check tightness