CAR CABIN FILTER: Anti-Pollution Filter With HEPA & Activated Carbon Purifying PM2.5 FILTER LAYERS: It consists of 5 different layers. EFFICIENCY: Its purification efficiency is 99.95%. PROTECTION: It blocks a high concentration of dust and dirt particles, pollen and second hand smoke from entering your lungs. PURIFICATION: The oxygen generating molecular sieve produces fresh, new oxygen. The catalyst removes the HCHO to improve the quality of the air.