Stage 8's Grade 8 Hex locking header bolts use a patented system that consists of a grooved hex-head bolt, a retainer, and a snap clip. The retainer fits over the bolt head and locks the bolt against the header tube, and the snap clip holds the retainer in place. Once Stage 8 header bolts are tightened down, they won't back out--eliminating leakage and blown header gaskets from loose bolts.