# Fuel cell cartridges or Fuel cell cartridges contained in equipment or Fuel cell cartridges packed with equipment containing flammable liquids · USPS — Mailing and air-carriage restrictions by item category For Fuel cell cartridges or Fuel cell cartridges contained in equipment or Fuel cell cartridges packed with equipment containing flammable liquids · USPS, item category is Fuel cell cartridges or Fuel cell cartridges contained in equipment or Fuel cell cartridges packed with equipment containing flammable liquids; carrier is USPS; restriction type is restricted; scope is domestic mail: surface only (air prohibited); conditions is Hazard class 3, UN3473, packing group not stated; domestic mail air: Prohibited; domestic mail surface: 3A, recorded from its source on 2026-08-30. - **Item category:** Fuel cell cartridges or Fuel cell cartridges contained in equipment or Fuel cell cartridges packed with equipment containing flammable liquids _(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, UN3473, packing group not stated; domestic mail air: Prohibited; domestic mail surface: 3A ## What the source says > Fuel cell cartridges or Fuel cell cartridges contained in equipment or Fuel cell cartridges packed with equipment containing flammable liquids 3 UN3473 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/).