This bolt is made from heat treated steel to grade eight spec's and is cad plated. This bolt fits most popular BBC Brodix, Dart, AFR, Edelbrock, World and RHS cylinder heads with long tube sheet metal valve covers. Bolts are sold separately and measure 4.250" under the head with .750" of course 1/4-20 thread, 3.375" of shoulder and a .437" six point head. Will not work with regular rail valve covers. Picture shows type of valve cover that the bolt is designed to be used with.