Denso oxygen sensors feature an aluminum-oxide trap layer to protect the ceramic from silicone and lead poisoning, preventing damage to the platinum electrode. Double protection cover maintains proper unit temperature for quicker response times and protects the ceramic element from contamination. Stainless steel housing resists corrosion and contamination with a rugged, watertight body. Porous PTFE filter allows atmospheric oxygen the enter the sensor without permitting water or engine contaminants to seep into the casing. Denso o2 sensors meet or exceed OE specifications.