Made from 3-layer polyester fleece material. Dustproof and high quality. The high-quality fleece filter bag autonomously cleans dust deposits inside the filter bag. When the vacuum cleaner is turned on, the self-cleaning filter bag inflates, and when the vacuum cleaner is turned off, the bag collapses. This process dislodges dust deposits inside the self-cleaning filter bag. For longer cleanliness and thus a longer-lasting high suction power. Efficient, clean, and health-conscious working with a system.