Blocked filters will reduce the suction in your vacuum cleaner. Cleaning and replacing your filters regularly will help to maintain its best performance. The high grade of material, used for these filters, provides your vacuum cleaner with a high filtration level and maximum dust retention. This kit includes 1x micro filter and 1x foam filter for Twintech ZT7740, ZT7750, ZT7770 vacuum cleaners. We recommend that filters should be replaced at least twice a year or when they become visibly soiled.