John Guest Speedfit Lowfit Spigot Socket Reducer 15mm X 12mmJG Lowfit manifold reducer allows any JG Underfloor Manifold port to be converted to a LowFit connection size of 12mm. Simply push the reducer into the JG Speedfit port on both flow and return bars. Manifold reducer with Speedfit connections Suitable for use with JG Speedfit PEX and polybutylene barrier pipe (inserts required) Suitable for underfloor heating applications only