A KN95 mask is a particulate-filtering facepiece respirator that meets the Chinese Standard of GB2626-2006 classification. This states a filtration efficiency  ≥95% of airborne particles.
KN95 respirators are considered functionally equivalent to certain respirators regulated under U.S.NIOSH standards however, slightly different criteria are used to certify their performance. The KN95 mask requires a fine mesh of synthetic polymer fibres, specifically a nonwoven polypropylene fabric. It is produced by melt blowing, and forms the inner filtration layer that filters out hazardous particles. The KN95 Respirator is designed to protect the wearer from non oily particulate matter, and aerosols.
CK Surgitech have added an additional 5th layer to this respirator, providing a high level of fluid resistance to 160mmHg
 
Characteristic / Spec
Particulate Filtration Efficiency  ≥95%
Fluid Resistance Penetration - 160mmHG