The JG 5/16" stem will fit 5/16" female push fit connector. John Guest 5/16. Stem to 3/8" Tube. Size 5/16" Stem to 3/8" Tube. Will not fit PVC tubing.
John Guest 3/8" Stem to 3/16" Tube Beer Line. JG Push-Fit Pipe Connector Reducer
3/16" Beer Line / Pipe & John Guest 3/8" Stem Reducer for Beer Tap & Keg Coupler
John Guest 3/8" Stem to 5/16" Tube Beer Line. JG Push-Fit Pipe Connector Reducer
6mm ID Flexible PVC CO2 Beer Gas Line with John Guest 3/8" OD Stem or Hose Clamp
Non Return Valve One Way SCV 5/16 8mm Push Fit 5 Pack Compatible JG John Guest
One Way Valve SCV Pushfit 3/8 9.5mm Ten Duotight Kegland Compatible John Guest