We are really pleased with this purchase of the 45i driftwood cover. The filter method works similar to others with 2 stages (initial carbon filter plus the HEPA filter). The controls are easy to understand and offer a lot of flexibility in how the system works. What's really wonderful is the way this looks. It's beautiful for a functional air filter - it's probably the nicest looking HEPA air filters on the market. We keep it in the bathroom with the kitty litter and it really helps keep the smell down.