ACDelco 748D GM Original Equipment Spark Plug Wire Set The same performance as your GM vehicles original factory component Spark plug distributor boot shape and materials provide proper fit, installation, and water-tight seal Terminal design improves spark plug retention and assists installation with excellent corrosion resistance Fiberglass braid and carbon impregnated fiberglass core for added strength and superior conductivity Engineered for electromagnetic interference and radio frequency interference (EMI/RFI) noise suppression