Three Part Slip Union primarily for installation maintenance. Middle Thread ring can be disengaged to separate the two halves of the Union without needing to recut or reglue. Integrated EPDM O-Ring prevents leakage when switching pieces in and out. PVC (polyvinyl chloride) is durable and resistant to corrosion. NSF Certified for potable water use. Not recommended for Gas or Pressurized air applications. Requires PVC Primer and Cement to bond with the pipe.