When the ambientair is contaminated with chemical, biological and radiation agents, the mask can provide effective protection ♥MF18B type gas mask Specifications: cyanogen chloride service lifeFoggy-poof propertyOil mist penetration coefficientVisual filedInhalation resistanceExhalation resistanceWeightMF18B type gas masksingle canister≥50min,bi-canisters'service life:2times of that of single one ...