Fit Model: ZouHwaSo 45i filter replacement is perfectly compatible with 45i air purifier model, original model number is B4-Fresh or FL40-Silver-Carbon. Please check your required model and size again before placing an order to avoid making a wrong purchase High-Quality Materials: 45i filter HI3 HEPA even spacing, clear pleats, reduce wind resistance, rapid air circulation; High efficiency activated carbon filled evenly, increasing the contact area of gas and Activated Carbon, improving the performance of air purification and odor removal Regular Replacement: With the passage of usage times and time, the cleaning performance of 45i filter will gradually decrease, and even cause secondary air pollution. Therefore, we recommend to replace 45eplacement filters every 9-12 months Value For Money: ZouHwaSo 45i filter replacement set will provide excellent value for every penny you spend, we use higher quality materials, the product is more durable and more affordable, and there are several combination kits for you to avoid the need to frequently buy new filters, giving you a value-for-money shopping experience Buy with Confidence: When you buy Zouhwaso products, you will get premium products and 7x24 hours after-sales service, if you have any questions during the use, please send us an email, we are very honored to serve you