Protects spark plug wires from the extreme temperatures of headers and exhaust manifolds. Withstands 500ú F direct continuous and up to 1200 degrees F radiant. Eliminates misfires and possible engine damage from burnt wires. Fiberglass composite won't cause misfires by arching. Includes Hi-Temp Shrink Tubes for a sharp, finished appearance. Can be used on any any hose or wire up to 10mm.