Includes:
1 x - S-Type Coupler with 5/8" Male Beer and Gas threads
2 x - duotight 5/8" duotight to 8mm push in
1 x - Non-Return Ball or Torpedo check piece (Non-Return Liquid)
1 x - Gas Duck Bill valve (Non-Return Gas)

How to install Gas Duck Bill Valve
Remove black EPDM washer inside 1 of the duotight push in fittings that you will use for gas. The duck bill valve is a washer as well as a non-return check piece.
It is optional, you do not have to use the non-return check pieces for gas or liquid.