1st layer: PP non woven 2nd layer: Melt blown filter paper 3rd layer: PP non woven ( Customized fabric is welcome) Bacterial filtration efficiencyï¼?>95 or 99% optional Size: Adultï¼?17.5*9.5cm Childrenï¼?14.5*8.5cm Infantï¼?12.5*7.5cm Packing: 50pcs/box,40box/ctn