The Apollo Expansion PEX 1/2 in. Plastic PEX-a Barb 90 Elbow (10-Pack) is simple to install. Apollo Expansion PEX poly alloy fittings are the perfect alternative to brass in regions where water quality can negative affect brass. Apollo PEX barb fittings are a key component of the most economical potable water piping systems. Also capable of integration into hydronic heating systems, Apollo Expansion PEX couplings must be secured into place using a Apollo Expansion PEX sleeve or comparable cold expansion-type sleeve or ring (all sold separately). The Apollo Expansion PEX system is a comprehensive cold expansion piping system comprised of brass fittings, poly alloy fittings, manifolds, valves, fasteners, tools and tubing designed for implementation in water delivery systems, simple or complex.