Quicksilver 805759Q3 Distributor Cap Kit - Marinized V-8 Engines by General Motors with Thunderbolt IV and V HEI Ignition Systems Cap is made from a blend of PBT and PET plastics for increased strength, stiffness and resistance to warpage Produced to meet Mercury Marine original equipment manufacturer specifications to best protect your MerCruiser engine Solid brass inserts resist corrosion and electrical pitting for long service life High strength to weight ratio for durability and resistance to thermal cracking Designed to resist RFI interference with onboard electronics