Nobody likes water leaks. And here's ARP's contribution to the solution. These premium grade bolts are engineered to properly engage the manifold threads and resist loosening. They're application-specific, and come in your choice of black oxide finished chrome moly or rust-proof stainless steel, with handy 12-point or standard hex heads. Washers included. Thermostat Housing Bolts 12Point Head Material Stainless Steel UHL 20mm