This kit is a Grade 8 Stainless Steel ARP (American Racing Products) crank pulley bolt & washer kit for the Ford 351-400M V-8 engines. These are not only good looking, and don't rust, but they are super strong and have a polished finish. These bolts have a tensile strength of 170,000 psi. They have a 6 point head and a .625 diameter flange for easier access in the tight spots. This kit also includes AN stainless washers.