3,204 records

Can I mail this item, or fly with it?

3,204 records covering 3,014 item categories, one fact each. Every value is transcribed from the source that states it and carries the sentence it was taken from: 47 sources across 21 sites, last checked 2026-09-08, due for re-check by 2027-09-08. Every record has a page of its own, quoting the line that states it.

12 records where two or more sources state different values. Both sides are reproduced on the record page, each with its own source and quote.

About this data

What item categories may be mailed, and what may be carried by air, with the conditions that apply. The spine is the USPS domestic mailability list (Publication 52, Appendix A) — about 90% of records. Alongside it: UK postal (Royal Mail, Post Office, Parcelforce, Royal Mail Wholesale), the UPU prohibited-articles entries for the US and UK, and about 116 records that are not about mail at all but about US air transport — passenger baggage and air cargo under FAA PackSafe, TSA, IATA and ICAO packing instructions, and 49 CFR. All three private couriers are covered as of 2026-09-01: FedEx (the International Connect prohibited and restricted item lists), UPS (the US Tariff/Terms and Conditions of Service — the items not accepted for transportation, plus the commodity sections on alcohol, marijuana and hemp, biological substances, firearms and ammunition, dry ice, limited quantity packages, hazardous waste and mercury, live animals, perishables, portable electronic devices, and tobacco and vaping), and DHL Express US (the prohibited commodities and the items needing prior approval, from DHL's own US 'what can I ship' page). Answers 'can I mail a lighter', 'USPS lithium battery mailing rules', 'can I fly with a power bank' and 'is [item] prohibited or restricted by [carrier]'. The carrier and scope fields on each record say which question it answers: a rule about carry-on baggage is not a rule about mail.

The data

Showing the first 400 of 3,204 records. Every record has its own page, with its source and the quoted line that states it; these list the rest.

• Records 1–400Spare (uninstalled) lithium ion batteries … Copper based pesticides, liquid, toxic · USPS · III
• Records 401–800Copper based pesticides, liquid, toxic, flammable, flashpoint not less than 23° C · USPS · III … 3,3’-Iminodipropylamine
• Records 801–1,2003,5-Dichloro-2,4,6-trifluoropyridine … Calcium chlorite
• Records 1,201–1,600Calcium cyanamide with more than 0.1 percent of calcium carbide … Dinitropropylene glycol
• Records 1,601–2,000Dinitroresorcinol, dry or wetted with less than 15 percent water, by mass … Iodine pentafluoride
• Records 2,001–2,400Iodomethylpropanes … Nitrogen trioxide
• Records 2,401–2,800Nitroglycerin, desensitized with not less than 40 percent non-volatile water insoluble phlegmatizer, by mass … Self-reactive liquid type E
• Records 2,801–3,200Self-reactive liquid type E, temperature controlled … Zirconium picramate, wetted with not less than 20 percent water, by mass
• Records 3,201–3,204Zirconium powder, dry … Zirconium tetrachloride

Where this came from

Every record above links the page it was taken from and quotes the sentence that states it. These are the 47 sources this dataset was assembled from.

• faa.govhttps://www.faa.gov/hazmat/packsafe/lithium-batteries
• dhl.comhttps://www.dhl.com/us-en/home/express/help-and-support/frequently-asked-questions/getting-started/what-can-i-ship.html
• faa.govhttps://www.faa.gov/hazmat/safecargo/icao-lithium-battery-summary-chart
• faa.govhttps://www.faa.gov/hazmat/packsafe/printable-chart
• fedex.comhttps://www.fedex.com/content/dam/fedex/us-united-states/shipping/fedex-international-connect-global-prohibited-and-restricted-items.pdf
• pe.usps.comhttps://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf
• iata.orghttps://www.iata.org/contentassets/05e6d8742b0047259bf3a700bc9d42b9/lithium-battery-guidance-document.pdf
• lion.comhttps://www.lion.com/lion-news/october-2024/lithium-battery-30-state-of-charge-recommendations-for-2025
• danielstraining.comhttps://danielstraining.com/revised-packing-instructions-for-lithium-cells-and-batteries-effective-03-31-22/
• upu.inthttps://www.upu.int/UPU/media/upu/files/postalSolutions/programmesAndServices/postalSupplyChain/customs/prohibitedArticles/ListOfProhibitedArticles.pdf
• corporate.postoffice.co.ukhttps://corporate.postoffice.co.uk/media/w5dlus1c/foia-response_foi2025_00179_appendix-d_rm-dangerous-goods-and-prohibited-and-restricted.pdf
• postoffice.co.ukhttps://www.postoffice.co.uk/mail/what-can-i-send
• royalmailwholesale.comhttps://www.royalmailwholesale.com/mint-project/uploads/233157117.pdf
• tsa.govhttps://www.tsa.gov/travel/security-screening/whatcanibring/items/lithium-batteries-100-watt-hours-or-less-device
• ups.comhttps://www.ups.com/assets/resources/webcontent/en_US/terms-service-us.pdf
• federalregister.govhttps://www.federalregister.gov/documents/2025/09/02/2025-16802/notice-of-implementation-of-the-presidents-executive-order-14324-suspending-duty-free-de-minimis
• federalregister.govhttps://www.federalregister.gov/documents/2026/06/24/2026-12670/indefinite-suspension-of-the-de-minimis-exemption-for-merchandise-arriving-through-all-modes-other
• ecfr.govhttps://www.ecfr.gov/current/title-49/subtitle-B/chapter-I/subchapter-C/part-172/subpart-B
• ecfr.govhttps://www.ecfr.gov/current/title-49/subtitle-B/chapter-I/subchapter-C/part-173/subpart-B/section-173.22
• law.cornell.eduhttps://www.law.cornell.edu/cfr/text/49/172.101
• pe.usps.comhttps://pe.usps.com/text/pub52/pub52c3_027.htm
• pe.usps.comhttps://pe.usps.com/text/pub52/pub52c3_022.htm
• selleressentials.comhttps://selleressentials.com/usps-hazmat-noncompliance-fee-2026/
• pe.usps.comhttps://pe.usps.com/text/pub52/pub52c3_021.htm
• blog.poshmark.comhttps://blog.poshmark.com/2026/07/09/59935/
• valueaddedresource.nethttps://www.valueaddedresource.net/poshmark-cover-usps-hazardous-non-compliance-fee/
• usps.comhttps://www.usps.com/ship/shipping-restrictions.htm
• pe.usps.comhttps://pe.usps.com/text/pub52/pub52c4_010.htm
• pe.usps.comhttps://pe.usps.com/text/pub52/pub52c4_009.htm
• pe.usps.comhttps://pe.usps.com/text/pub52/pub52c3_026.htm
• pe.usps.comhttps://pe.usps.com/text/pub52/pub52c3_025.htm
• pe.usps.comhttps://pe.usps.com/text/pub52/pub52c3_024.htm
• pe.usps.comhttps://pe.usps.com/text/pub52/pub52c4_026.htm
• pe.usps.comhttps://pe.usps.com/text/pub52/welcome.htm
• pe.usps.comhttps://pe.usps.com/text/pub52/pub52c4_020.htm
• pe.usps.comhttps://pe.usps.com/text/pub52/pub52c4_027.htm
• pe.usps.comhttps://pe.usps.com/text/pub52/pub52c3_028.htm
• ecommercebytes.comhttps://www.ecommercebytes.com/2026/07/05/new-usps-noncompliance-fee-could-take-sellers-by-surprise/
• pe.usps.comhttps://pe.usps.com/text/pub52/pub52c3_020.htm
• pe.usps.comhttps://pe.usps.com/text/pub52/pub52c3_023.htm
• pe.usps.comhttps://pe.usps.com/text/pub52/pub52c5_009.htm
• pe.usps.comhttps://pe.usps.com/text/pub52/pub52c4_006.htm
• pe.usps.comhttps://pe.usps.com/text/pub52/pub52c4_005.htm
• pe.usps.comhttps://pe.usps.com/text/pub52/pub52c4_014.htm
• pe.usps.comhttps://pe.usps.com/text/pub52/pub52c4_018.htm
• pe.usps.comhttps://pe.usps.com/text/pub52/pub52c5_008.htm
• pe.usps.comhttps://pe.usps.com/text/pub52/pub52c4_015.htm

Machine-readable

• data.jsonThe whole dataset — every record with its source URL and source quote.
• Open Knowledge Format bundleOne JSON object per line — every record's frontmatter and quoted span exactly as it is held here, in one fetch.
• data.csvThe same records as one flat table, for a spreadsheet or a dataframe. The last four columns are the source URL, the quoted sentence it was read from, the date we last checked it, and which columns are our reading rather than the page's words.
• How this is made and checkedWhat "verified against source" does and does not mean.

From your own code

Same records, same quotes, without scraping the page: refsource is on PyPI and npm. Each value comes back carrying the URL it was read from and the sentence on that page that states it — .source and .quote sit on the value itself rather than in a side channel, so the checking step is available instead of skipped.

pip install refsource
refsource lookup shipping-restrictions-by-class carrier="Airlines (all US carriers)"

npx -y refsource lookup shipping-restrictions-by-class carrier="Airlines (all US carriers)"

Set your AI assistant up to use this

Two files and no account. Put this in .mcp.json at the root of your project — Claude Code, Cursor, Windsurf, VS Code and Codex all read that file — and your assistant can look this dataset up instead of recalling it. The server is remote, keyless and read-only.

{
  "mcpServers": {
    "referencesource": {
      "type": "http",
      "url": "https://referencesource.org/mcp"
    }
  }
}

Add to Cursor · or, on the command line: claude mcp add --transport http referencesource https://referencesource.org/mcp --scope project

Then one line in the project's CLAUDE.md or AGENTS.md, so the assistant knows when to reach for it:

When a question needs "Mailing and air-carriage restrictions by item category", call the referencesource MCP server at https://referencesource.org/mcp (tool `search_records`, dataset_slug `shipping-restrictions-by-class`) instead of answering from memory — every record it returns carries its source URL and a verbatim quote from that page.

What each tool does, and the servers built over single registers: Connect your AI assistant.

3,204 records. last verified against source 2026-09-08. due for re-check by 2027-09-08.

Licence. Facts extracted from public government and postal service web pages; not a reproduction of the original text