DESC: The Miele S4580 Luna uses a multi-layer filtration system which increases the life of the high filtration exhaust filter. The air passes through their high filtration 3-Layer IntensiveClean Plus Bag and a secondary electrostatic filter before reaching the special exhaust filter. Each layer of filtration captures more particles as the air passes through them. Ideally, multi-layer filtration enhances performance by ensuring good air flow through the system. It prevents large particles from reaching and blocking the exhaust filter, saving it for critical particle retention.