Always use a JG Speedfit superseal pipe insert when connecting Speedfit pipe to a Speedfit push-fit fitting. Inserts play a vital role in providing extra support to pipework, ensuring that the ends of the pipe are kept nice and round, and minimising any loss of shape that can occur when cutting. JG Speedfit superseal pipe insert contains dual o-rings to provide even greater sealing security than a standard insert. The first o-ring is on the stem that is pushed into the pipe to prevent water from inside the pipe passing between the inside of the pipe wall and the outside surface of the insert. The second o-ring sits on the end of the insert and seals inside the push-fit fitting, becoming a seal between the main pipe and push-fit fitting. When superseal Inserts are used with Speedfit push-fit fittings a multi-seal is formed as all push-fit fittings also include a main o-ring seal. 2 extra O-Rings provide enhanced sealing Maintains structural integrity of the pipe connection Helps make the pipe more rigid when a side load is applied Suitable for hot and cold water and central heating systems Suitable for Speedfit pipes and fittings only