Extreme heat expands metal that then shrinks when it cools. This is why headers bolts loosen. With Spectre’s Lockwire Header Bolts, heat is one-upped in a simple fool-proof way. Utilizing stainless steel wire wrapped with a spring to hold tension, you simply insert the lockwire into the pre-drilled and iridite-plated bolts once properly torque. Simple, effective and just one of the Spectre fasteners that make doing the job easier and better.