# Combustible Liquids (Hazard Class 3) — Postal shipping restrictions by item category

For Combustible Liquids (Hazard Class 3), carrier is USPS; restriction type is restricted; scope is Domestic Mail via Air Transportation (as ID8000) or Surface Transportation (as Limited Quantity); prohibited International; conditions is Via air, mailable if they qualify as ID8000 materials per 335 and meet criteria in Exhibit 343.22. Via surface, mailable if they qualify as Limited Quantity and consumer commodity materials per 343.22. Prohibited in international mail, recorded from its source on 2026-08-04.

- **Item category:** Combustible Liquids (Hazard Class 3)
- **Carrier:** USPS _(our reading, not quoted from the source)_
- **Restriction type:** restricted _(our reading, not quoted from the source)_
- **Scope:** Domestic Mail via Air Transportation (as ID8000) or Surface Transportation (as Limited Quantity); prohibited International _(our reading, not quoted from the source)_
- **Conditions:** Via air, mailable if they qualify as ID8000 materials per 335 and meet criteria in Exhibit 343.22. Via surface, mailable if they qualify as Limited Quantity and consumer commodity materials per 343.22. Prohibited in international mail. _(unconfirmed — we could not tie this to the quote below)_

## What the source says

> //pe.usps.com/text/pub52/pub52c3_022.htm> 343 Flammable and Combustible Liquids (Hazard Class 3) <https://pe.usps.com/text/pub52/pub52c3_023.htm> 344 Flammable Solids (Hazard Class 4) <https://pe.usps.com/text/pub52/pub52c3_024.htm> 345 Oxidizing Substances, Organic Peroxides (Hazard Class 5) <https://pe.usps.com/text/pub52/pub52c3_025.htm> 346 Toxic Substan

## Source

- https://pe.usps.com/text/pub52/welcome.htm

Last verified: 2026-08-04. Review by: 2027-08-04.
Part of [Postal shipping restrictions by item category](https://referencesource.org/shipping-restrictions-by-class/).