Jg12i vs Jg38: specs compared
Updated 05 September 2026.
12.7 mm
Jg12i wins on tube outer diameter
On tube outer diameter, Jg12i leads: 12.7 mm versus 9.53 mm.
| Spec | Jg12i | Jg38 |
|---|---|---|
| Designation | 1/2" (12.7 mm) OD | 3/8" (9.5 mm) OD |
| Size / thread | 1/2" (12.7 mm) OD tube | 3/8" (9.53 mm) |
| Fitting form | push-fit collet, imperial | push-fit collet, imperial |
| Seals on | single O-ring plus a stainless collet grab-ring | single O-ring plus stainless collet grab-ring |
| Rating / role | John Guest Speedfit imperial fittings for 1/2 inch OD tube | Speedfit acetal fittings rated to 12 bar at 20 C, 6 bar at 65 C |
| Tube OD | 12.7 mm | 9.53 mm |
Questions and answers
Which has the higher tube outer diameter, Jg12i or Jg38?
On tube outer diameter, Jg12i leads: 12.7 mm versus 9.53 mm.
How do Jg12i and Jg38 compare?
On tube outer diameter, Jg12i leads: 12.7 mm versus 9.53 mm.