The next generation of advanced carbon filters, the Classic 200 Series DualProtection filter, is designed to achieve ultimate particle, gas and odor removal. This replacement filter is compatible with the following Blueair models; Classic 205 and Classic 280i. Pure, high-porosity coconut carbon efficiently traps gaseous pollutants from your home, including household chemicals and cleaners, volatile organic compounds (VOC) and odors from pets, cooking, and smoking. To maintain optimum performance, we recommend changing your filter about once every 6-months when used 24 hours a day.