A 38-400 neck finish specifies a 38mm outer thread diameter with a single-turn continuous thread profile. In Glass Packaging Institute (GPI) standards, this designation indicates the exact closure dimension needed to seal 1 gram glass, 1 gram PET, and 84mm glass jar bases without liquid or gas leakage.

To cross-reference specs before ordering, check technical specification tables inside each product listing.

• 38mm Thread Standard: GPI 400 thread height accommodates continuous thread closures for dabs, rosin, and extracts.
• Barrier Integrity: Heavy-wall glass and PET construction prevents terpene loss when properly torqued.

No, 38mm glass and PET jars are sold as standalone bases and require separate 38-400 closures. Pairing 38mm jar bases with continuous-thread 38mm push-and-turn safety caps ensures compliance under Title 16 CFR 1700.20 and ASTM D3475 child-resistant standards.

Browse matching closures in our 38mm Caps Collection, check dimensions on our Flower Jar Sizing Chart, or review legal packaging rules via our State Compliance Regulations Guide.

Inventory ships directly from our local Sacramento warehouse so clients can access single units, standard split packs, or master wholesale cases without minimum constraints. Local warehouse stocking eliminates long factory lead times and keeps commercial filling lines operating continuously.