Keep you and your employees safe while working in caustic fumes and airbourne irritants. Great for construction work, painting, sanding, mold remediation, chemical cleaning, extermination or other types of airbourne contaminents or chemical vapors. Set of 2 replacment Filter Cartridges For Sperian Half Face Mask Respirators or any other respirator that requires a 3.5 diameter round cartridge. • Half Mask Respirator Filter Replacement Cartridges • Fits Sperian or Other 3.5 Round Respirators Perfect for Sanding, Painting, Chemical Application and More