# Butanedione · USPS — Mailing and air-carriage restrictions by item category

For Butanedione · USPS, item category is Butanedione; carrier is USPS; restriction type is restricted; scope is domestic mail: surface only (air prohibited); conditions is Hazard class 3, UN2346, packing group II; domestic mail air: Prohibited; domestic mail surface: 3A, recorded from its source on 2026-08-30.

- **Item category:** Butanedione _(verified: appears in the quote below)_
- **Carrier:** USPS _(our reading, not quoted from the source)_
- **Restriction type:** restricted _(our reading, not quoted from the source)_
- **Scope:** domestic mail: surface only (air prohibited) _(our reading, not quoted from the source)_
- **Conditions:** Hazard class 3, UN2346, packing group II; domestic mail air: Prohibited; domestic mail surface: 3A

## What the source says

> Butanedione 3 UN2346 II Prohibited 3A

## Source

- https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf

Last verified: 2026-08-30. Review by: 2027-08-30.
Part of [Mailing and air-carriage restrictions by item category](https://referencesource.org/shipping-restrictions-by-class/).