Any good mechanic will tell you - use the very best components available. DENSO First Time Fit® engine sensors are specifically designed to meet the challenging demands of today's automobile systems. Each of DENSO's sensors is constructed of the highest quality materials available. High-quality stainless steel, porous polytetrafluoroethylene (PTFE), fluorine rubber, aluminum oxide, high-grade platinum and ceramics are used in each DENSO sensor. The bottom line is: DENSO produces the finest sensors in the world.