1. Clean brushes keep your home robot operating at peak performance. 2. Side brushes are easy to remove and replace as part of routine maintenance. 3. Replacement filters for Xiaomi Roborock S50 S51 Vacuum Cleaner Robots. 4. Filters maintain robot's cleaning performance while reducing infiltration of dust, pollen and other allergens into the air you breathe. 5. For best results, filters should be replaced every 2 - 3 months.