Specifications: 1. Time of gas defence:depending on the canister. 2. Exhalation resistance: ≯98 pa at 30L/min. 3. Visual field: total ≮ 75°, binocular visual field ≮30°. 4. Oil mist penetration coefficient: ≯0.005 at 30L/min. 5. Leakage of mask: ≯0.005% 6. Storage life:5 years in condition that canister shall be stored stated as follows.