... of resembling graphite microchip and milk-layer stack.2.activated carbon fiber cassette is made by activated carbon fiber,and the outer surface is ... , ACF mask has properties as: gas defense, deodorize, germ filter, dust preventer and so on specificationsurface area 900-1100m2/g, 1200-1300m2 ... make any shape,eg the roundness,the square,hollow form,and so on. activated carbon filter cassette(YH-232)