These masks offer at least 95% filtration efficiency against certain non-oil based particles and aerosols. They feature Cool Flow Exhalation Valve that helps release the warm and moist exhaled breath from inside the respirator. They include an adjustable M-noseclip and stretchable, braided headbands. Price drops from $19.97 to $4.97. Free shipping over $35+ otherwise it adds $5.99.