Under sink filters: 1.Standard 5 stage RO system 2.Standard filter ,buy ... :50%RO 5 stage systemFilter PP, GAC, CTO 50G CSM membrane 3.0G pressure storage tankStainless steel drinking water tap With ... of tats,odor ,and color.Stage 4:(RO)Reverse osmosis membrane ,thins film composite high quality membrand taht processes 50GPD,it ...