210/case (6 boxes of 35), 99.5% Filtration Efficiency @.1 Micron per ASTM F2299. - The PFL Laser Mask filters plumes during laser surgery. The mask uses the advanced technology Positive Facial Lock® with the Twist-Seal® chin piece to give everyone in the operating room a custom, no-gaps fit regardless of face size or shape. The PFL design helps eliminate the potential of inhaling small particles around the edge of the mask. The patented Magic Arch® keeps the mask away from the nose and mouth for cooler, more comfortable breathing action...without restricting downward vision. These durable masks are made of hypoallergenic material and have a smooth, soft interior for ultimate comfort.