The retention of 8μm is slightly stronger than that of Grade1, but the filtration time is relatively long (that is, the velocity of filtration is relatively slow), and the adsorbability is stronger than that of Grade 1, and Grade 2V is folded well. In addition to the ordinary filtration of 8 M size particles, its additional adsorption properties are also used, for example, to intercept soil nutrition in plant growth experiments and to monitor special pollutants in air and soil tests.