... carbon and it dont put our nitrite during the process of removing chlorin.2, multilayer empty-middle filar velumFilar velum ... made in japan, on the surface there are lots of 0.1micron particulate,the particulate laps over and form multilayer ... bacteria,coliform,hold back protoplast feculent things,get rid of chlorin(chloride of lime),firedamp,impurity,rust,color,odor,pesticide and granule,reserve ...