John Guest 12mm push-fit: 12 mm OD tube, push-fit collet, metric, seals on single O-ring plus a stainless collet grab-ring. What it fits and the adapters to join it to other keg fittings.
Updated 05 September 2026.
John Guest 12mm push-fit (12 mm OD)
Where 12 mm OD is used, its real dimensions, and how to connect it to other keg fittings.
Published dimensions
- Designation
- 12 mm OD
- Size / thread
- 12 mm OD tube
- Fitting form
- push-fit collet, metric
- Seals on
- single O-ring plus a stainless collet grab-ring
- Rating / role
- John Guest Speedfit metric fittings for 12mm OD tube
- Tube OD
- 12 mm
Used on: long draw and trunk beer lines on European draft systems specified in metric.
12mm is one of the larger John Guest metric sizes, used on longer beer runs where a wider bore reduces pour resistance. It is metric only and does not take 1/2 inch imperial tube, so match the collet to the printed 12mm OD.
Flare fittings seal on the 45 degree flare face and must never be taped. Push-in fittings seal on an O-ring against the tube wall and need the tube cut square. Barbs seal under a worm clamp. Getting the sealing method right matters more than the thread label, because most homebrew leaks are a taped flare or an unclamped barb.
Connect this fitting
Questions and answers
What is the designation of the John Guest 12mm push-fit (12 mm OD)?
12 mm OD
What is the size / thread of the John Guest 12mm push-fit (12 mm OD)?
12 mm OD tube
What is the fitting form of the John Guest 12mm push-fit (12 mm OD)?
push-fit collet, metric
What is the seals on of the John Guest 12mm push-fit (12 mm OD)?
single O-ring plus a stainless collet grab-ring