Post Firestone vs G5/8 regulator inlet (G5/8 (BSP parallel)): specs compared
Updated 05 September 2026.
5
specs differ
Post Firestone and G5/8 regulator inlet (G5/8 (BSP parallel)) differ on 5 specs: designation, size / thread, fitting form, seals on, rating / role.
| Spec | Post Firestone | G5/8 regulator inlet (G5/8 (BSP parallel)) |
|---|---|---|
| Designation | 9/16"-18 UNF | G5/8 (BSP parallel) |
| Size / thread | 9/16"-18 UNF (about 14.3 mm major) | G5/8 (5/8" BSP parallel) |
| Fitting form | UNF male post thread | parallel pipe thread, regulator side |
| Seals on | poppet inside the post; post base O-ring seals to the keg lid | flat washer on the face of the inlet |
| Rating / role | gas and liquid posts share the thread; disconnect snaps over the outside | a common regulator inlet thread that a CGA-320 or W21.8 adapter presents |
Questions and answers
How do Post Firestone and G5/8 regulator inlet (G5/8 (BSP parallel)) compare?
Post Firestone and G5/8 regulator inlet (G5/8 (BSP parallel)) differ on 5 specs: designation, size / thread, fitting form, seals on, rating / role.