Pentair Pentek Slim Line Filter Housings are available in either reinforced polypropylene or clear Styrene-Acrylonitrile (SAN) in 5", 10" and 20" lengths. The black or blue reinforced polypropylene housing caps are available with 1/4", 3/8" or 1/2" NPT connections. Four bosses are molded into every cap for mounting purposes. They are equipped with a black, reinforced polypropylene cap and offer an optional pressure-relief button on the inlet side to relieve pressure inside the housing when changing filter cartridges. Opaque Slim Line Filter Housings, molded from rugged reinforced polypropylene, offer outstanding chemical compatibility and are ideal for use in a variety of low-flow applications. These applications include undersink and countertop residential filtration, pre- and post-reverse osmosis filtration, recreational vehicle filtration, foodservice and humidifying systems. Clear Slim Line Filter Housings offer on-site examination of flow, performance, and cartridge life. They are also ideal for a variety of applications.