Miele HA-30 HEPA filter fits in S2, S7 and older S200-S700 series Miele vacuums. This filter has a true HEPA filtration layer that removes 99.95%+ of microns .1 or greater in size. Combined with a rubber air tight sealing system around the sides of the filter, you have the ideal setup for allergy sufferers or anyone looking to enjoy a higher quality of air in their home. Miele has recommended changing once a year for standard user volumes (or approx. 50hrs of use). To help users remember when to change their filters, a time release color strip has been added. This strip slowly fills with red until after one years time, the whole strip becomes red.