Jg12 vs JG4: specs compared
Updated 05 September 2026.
12 mm
Jg12 wins on tube outer diameter
On tube outer diameter, Jg12 leads: 12 mm versus 4 mm.
| Spec | Jg12 | JG4 |
|---|---|---|
| Designation | 12 mm OD | 4 mm OD |
| Size / thread | 12 mm OD tube | 4 mm OD tube |
| Fitting form | push-fit collet, metric | push-fit collet, metric |
| Seals on | single O-ring plus a stainless collet grab-ring | single O-ring plus a stainless collet grab-ring |
| Rating / role | John Guest Speedfit metric fittings for 12mm OD tube | John Guest Speedfit metric fittings for 4mm OD tube; tube OD must be within 0.1mm of nominal |
| Tube OD | 12 mm | 4 mm |
Questions and answers
Which has the higher tube outer diameter, Jg12 or JG4?
On tube outer diameter, Jg12 leads: 12 mm versus 4 mm.
How do Jg12 and JG4 compare?
On tube outer diameter, Jg12 leads: 12 mm versus 4 mm.