it is micro-layer,and can be divided into precision microporous filter 20*100 mesh,microporous 40 mesh,precision microporous 20*100 mesh,outer protective coat.it's feature cantain:1,acid resistance,alkali resistance,slat resistance,corrosion resistance.2,large filtration area,high rate of oil.3,uniform hole,high-performance of  permeability and blockade.4,high deformation resistance