Post Firestone vs GU Thread Adapter: specs compared
Updated 05 September 2026.
5
specs differ
Post Firestone and GU Thread Adapter differ on 5 specs: designation, size / thread, fitting form, seals on, rating / role.
| Spec | Post Firestone | GU Thread Adapter |
|---|---|---|
| Designation | 9/16"-18 UNF | 13/16"-14 to 7/8"-14 |
| Size / thread | 9/16"-18 UNF (about 14.3 mm major) | 1/2" BSP (13/16"-14) one end, 5/8" BSP (7/8"-14) the other |
| Fitting form | UNF male post thread | port thread adapter |
| Seals on | poppet inside the post; post base O-ring seals to the keg lid | flat washer on each threaded face |
| Rating / role | gas and liquid posts share the thread; disconnect snaps over the outside | converts the 1/2" BSP (13/16"-14) beer port some G and U couplers carry to the 5/8" BSP (7/8"-14) standard |
Questions and answers
How do Post Firestone and GU Thread Adapter compare?
Post Firestone and GU Thread Adapter differ on 5 specs: designation, size / thread, fitting form, seals on, rating / role.