Combining the same practical protection of our premium filters with a price point that's tough to beat, our DOTPro 320 respirator filters give you the best bang for your buck when you're stocking up for yourself, your family, or your organization. Flexible, affordable, and built to last with a shelf life of 7.5 years, DOTPro 320 NBC filters may provide exactly the kind of protection you're looking for. Key Features: 40 mm x 1/7" NATO filter standard (EN 148-1:1999) threading Built to comply with a wide variety of international standards, including EN 14387:2004+?1:2008, EU Health and Safety requirements Full Spectrum protection from NBC/ABE Mfg: Mira Safety