A frame bolt is a Grade-8 indented hex flange screw with a recessed fillet radius.

This added feature improves joint integrity by providing a more uniform bearing surface with drilled or punched holes. Most truck and auto rebuilders prefer this undercut feature to the O.E.M. product.

Hill Fastener provides them from high-grade alloy steel to meet or exceed 150,000 p.s.i. tensile strength.