APEC''s 50 GPD Essence reverse osmosis membranes are effective filtration elements that have been designed to deliver high contaminant rejection rates at high input TDS levels. These industry standard 10" membranes use an industry leading state-of-the-art TFC (Thin Film Composite) design to provide high quality water for a broad range of water chemistries. They will fit in most commonly available housings to provide ultra pure and safe reverse osmosis drinking water. For ROES-50 Essence Reverse Osmosis system High contaminant rejection RO element TFC spiral wound design for superior membrane flux Effective under varying water conditions with wide operating limits Industry standard sized membrane