For best results, use a clean filter at the beginning of each beauty treatment. Check after several minutes of use to see if the filter is getting clogged with dead skin cells. Depending on how long you use the device, you may need to change the filter during a beauty treatment. Discard filter after each use. Only filters purchased from Kelley West Microderm360 will fit this machine. All others will invalidate the Conditional Manufacturer's Warranty.