... other components, the Department may need to adjust themselves with elastic. 2 major technical indicators 2.1 Protection Time (benzene): ≥ 20 ... strap length, a mask must be kept upright, align the face, wrap your mouth and nose, nose, both sides should not have ... the mask is not loose, do not squeeze the nose face, do not leak. 3.4 inhale microleakage test, do not ...