... according to FDA by adopting advanced technology ,the raw material of outer cover is high-quality stainless steel ( ... it has big filtering area and low rate of clogging , if filters fast without contaminating and ... , 20 inch , 30 inch , 40 inch . The material of filter core has teflon , polysulfone , nylon ,pp and ... acetate .The hole diameter of filter is 0.1μm, 0.22μm , ...