Polypropylene Filter Sheets for face mask

• (5) POLYPROPYLENE FILTERS. • Dimension 5" (=13 cm) x 3.2" (=9 cm), you can trim to fit your face mask. • Our face mask filters are made from the same materials as medical-grade face masks in accredited factories in Korea. All filters have passed the standard filtration efficiency tests. Filtration Efficiency of 99.9%. • You can use one filter continuously for 16 hours, around 1 week of occasional use (or whenever it becomes harder to draw breath). These filters are hand-washable one time and machine-dryable. • All filters are not intended for Clinical use.