From the product description, check product page for current description, price and availability:

The Duotight Flow Stopper is a handy devicie to use while filling kegs or when transferring between kegs during filtering or after fining. Simply attach the Flow Stopper to the gas post of your keg, then when the keg is full it will automatically cut off flow and prevent excess beer from exiting your gas post and spilling onto the floor.

For even better results, we recommend using the Flow Stopper with the BlowTie Spunding Valve. The BlowTie will enable you to apply head pressure to the keg, meaning you can control the flow speed and reduce the foam generated in the filling process. You will need a short length of 8 mm OD EVABarrier tubing to connect the BlowTie to the outlet of the Flow Stopper.

• • 2 x Duotight 8 mm x 5/8″ FPT (DUO104)
  • 1 x Duotight 8 mm elbow (DUO107)
  • 1 x Duotight 8 mm x 1/4 in. flare (DUO106)
  • 1 x Ball float
  • 1 x Stainless spring
  • 2 x 8 mm OD EVABarrier joiners
  • 1 x Acrylic sight glass

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