Masks have an outer layer of apertured polyethylene film to provide protection from contamination. Nonsterile face masks offer excellent breathability with filtration of 99% at 0.1um. These comfortable masks feature nonirritating BICOSOF inner facing and a bendable aluminum nosepiece. Sterile masks feature polyester binding and polyester filter media, which provides bacteria filtration efficiency (BFE) of 91.9% and particle filtration efficiency (PFE) of 93.1%. Sterile masks are gamma-sterilized to 10-6. Outer layer of apertured polyethylene film Nonsterile face masks features nonirritating BICOSOF inner facing and bendable aluminum nosepiece; filtration of 99% at 0.1?m Sterile face masks features polyester binding and polyester filter, filtration efficiency (BFE) of 91.9%, particle filtration efficiency (PFE) of 93.1%; SAL 10-6 Recommended for ISO Class 3 (FED-STD-209E Class 1/M1.5) or higher cleanroom environments.