Fel-Pro performance head gaskets feature a PermaTorque/blue gasket body with a solid-steel core to minimize torque loss and gasket blowout. Fel-Pro performance head gaskets also have a wire-ring combustion seat with stainless steel "armor" for extra sealing force around combustion chambers. Made with a pre-flattened steel-wire ring, Fel-Pro performance head gaskets have the strength of steel-wire sealing and the minimum brinelling of aluminum heads.