Multi Rounds FRP High Flow Cartridge Filter Housings can be used to place 3 rounds, 12 rounds, 34 rounds and 54 rounds high flow cartridge filters, supporting 40" and 60" lengths. The filter housing is made of FRP (fiber glass), suitable for filtering various corrosive liquids, mainly for seawater reverse osmosis (SWRO) and brackish water reverse osmosis (BWRO) prefiltration.