https://www.dhx-protectiveequipment.com/product/kn95-mask/kn95-nonsterile-medical-protective-mask.html Product name: KN95 non-sterile medical mask; Particulate filtration efficiency (PFE) ≥ 95%; Model: foldable ear-hook type, foldable strap type, foldable head-mounted type; Specifications: There are A, B, C, D, E, F, G, H, I, J, with a total of 11 specifications. Length×width respectively (16cmХ10.7cm, 14cmX9.5cm, 15.5cmX10.7cm, 17cmX10.7cm, 20cmX8cm, 18cmXI0.5cm, 20cmX7cm, 21cm×9.5cm, 17.5cmX9.5cm, 21.5cmX8cm, 13.5cmX9cm)