PM2.5 Carbon Replacement Filter Insert For Washable Face Masks. These can be inserted into any 2-layer cotton mask and replaced as necessary. The filter has the same layers on each side with a carbon filter in the middle, so there is no right or wrong side. A great addition to your homemade mask or to our Matter Mask and Fender Mask. This filter is good for up to 80 hours of light use before disposing.

Each PM2.5 filter is good for up to 80 Hrs of use, in everyday environments. If you are in a highly polluted environment of any sort, such as a factory or construction site, you will want to replace your filter sooner. Please be sure to dispose of any the used filters safely and clean your masks regularly.