The Centers for Disease Control recommend wearing face coverings in public settings. While a cloth mask alone provides a certain level of protection, disposable PM2.5 filters will filter out particles as small as 2.5 microns. Invest in the health and safety of yourself and others by using a PM2.5 filter. Each 5-layer filter is a combination of non-woven and meltblown cloth sandwiching an activated carbon layer. The filter slips easily into the inside pocket of all RainCaper reusable fabric face masks and fit many other masks on the market as well. The disposable PM2.5 filters should be replaced after 5 to 7 days of use. Filters are sold as a pack of 10 which arrive in a hygienically sealed poly bag.