DetailsTW30-1812 RO Membrane Housing - 304 Stainless Steel. #SS1812. Replaces plastic residential RO membrane housings. Your RO Reverse Osmosis system deserves the best membrane housing. Solid 304 Stainless Steel construction. Dual O-ring design to prevent leaks. This cast 304 Stainless Steel reverse osmosis membrane housing is the finest one we have ever seen. You will love this housing. It is the last membrane housing you will ever need to buy.