Seals the dust safely. The air in the room is cleaner after vacuuming than before. Change the filter once a year to maintain the unit's performance. Two filter types in one for trimming. Compatible with Compact C2 and Complete C1/C3 vacuum cleaners, as well as S 227 i - 240 i, S 247 i - 262 i, S 269 i - S 284 i, S 291, 300, 400, 500, 600, 700, 800, 2000, 4000, 5000, 6000, 8000, and Upright S7.