Designed exclusively for use within Type A PEX piping systems Full-flow design for maximum water output Used to make PEX-a to PEX-a connections using PEX-a tubing The Apollo Expansion PEX 3/4 in. Plastic PEX-A Barb Tee (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).