Magnetic snaps, magnetic gift boxes and battery-powered smart tags look like ordinary trims on an air waybill, but under air cargo rules they belong to a different class of goods. Many brands hit this on their first sample shipment: the parcel is held at origin pending a magnetic field report or UN38.3, and in development season a week disappears.

This guide covers three things: which trims get special handling by air, what the 0.418 A/m at 2.1 m magnetic limit actually measures, and how to prepare documents and packing for samples and bulk so the shipment clears first time.

1. Three Trim Categories That Get Special Handling

  • Magnetic hardware: neodymium snaps, magnet sheets in gift boxes, magnetic tag closures. The stronger the holding force, the likelier it exceeds the air limit; in bulk the fields add up, so a carton can fail where a single piece passed
  • Battery-powered smart labels: active NFC tags, Bluetooth trackers, temperature and humidity loggers. A passive NFC tag draws power from the phone and carries no cell, so it is usually not dangerous goods; add a coin cell and the rules change at once
  • Liquids and aerosols: ink, screen-print thinner, cleaner or spray adhesive travelling with samples. Most are flammable liquids needing an SDS and compliant packing; buy these locally rather than shipping them across an ocean

2. The Magnetic Threshold: 0.418 A/m at 2.1 Metres

In IATA rules, magnetized material is UN2807, Class 9 miscellaneous dangerous goods. The test is not holding force but field strength measured 2.1 m from the outside of the package: at or below 0.418 A/m (about 0.005 gauss) the shipment moves as general cargo; above it, you must declare dangerous goods, with special rates and packaging. The figure has nothing to do with pull strength — a small snap that merely holds two cards together can still fail in a carton if all its poles face the same way.

  • Who tests: a third-party lab or qualified body measures with the IATA method and issues a magnetic field report, usually per package configuration and quantity, valid for the period stated on it
  • When testing is mandatory: neodymium magnets, magnetic closures on gift boxes, bulk snap orders, and any batch a customer insists goes by air. Weak magnets such as thin sheets in gift boxes can be trialled with a small parcel first
  • How to lower the reading: alternate pole orientation, separate individual pieces, use a galvanised or tin-plate shielding box, and cap the number per carton. These reduce the reading but do not replace a report

3. Battery-Powered Smart Tags: UN38.3 Is the Entry Ticket

For anything with a cell going by air, the first document is always the UN38.3 test summary, proving the cell passed eight tests including altitude simulation, thermal cycling, vibration, shock and external short circuit. Only when the cell sits inside equipment and stays under the stated lithium content or watt-hour limit can the looser provisions be used; cells shipped loose, or many inside equipment, tighten the rules immediately. Lithium metal and lithium ion cells fall under different provision numbers and cannot be mixed up.

The more common trap is assuming there is no battery. Temperature loggers, Bluetooth trackers and illuminated tags can each hide a coin cell; the customer treats them as printed matter and ships them with garments, and the whole consignment is opened and reworked at the airport.

4. A Practical Checklist for Samples and Bulk

  • Ask the channel first: courier, air freight and sea freight follow different rules. Couriers apply their own, often stricter than air cargo, so ask the account manager for the acceptance requirements for that commodity before you pack
  • Three documents: magnetic field report for magnets, UN38.3 plus SDS for batteries, and a composition and use statement for everything. Describe the goods properly on the invoice — never just samples or gift
  • Pack it properly: alternate magnet polarity and separate pieces; protect cells against short circuit with original packaging, taped terminals and dividers; mark count and net weight on the carton instead of cramming everything into one box
  • Build in slack: plan two or three extra working days on a first shipment; magnetic testing and dangerous goods declarations are booked, not instant. If the customer is in a rush, courier one magnet-free confirmation parcel and move the bulk through the proper channel

5. Three Choices to Avoid at Design Stage

  • Over-speccing magnets: a paper box is often given neodymium magnets for feel when a very light hold would do. Switching to thin magnetic sheet or a magnetic closure patch drops the reading and the cost
  • Treating an active tag as printed matter: for most garment use cases a passive NFC inlay is enough — a phone reads it at close range, and no cell means no UN38.3 and no air restriction
  • Stuffing ink and glue into the sample box: adding thinner and spray adhesive to the courier parcel is the easiest way to get held. Buying one bottle locally costs far less than returning the whole consignment
💡 Tip: magnet and battery problems are almost always planted at development stage; fixing them at shipment means redesigning or switching air to sea. Put contains magnet or contains cell on the quotation as part of the specification — far easier than explaining later.

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Planning magnetic packaging or a chip-enabled smart tag? Send the construction, destination market and expected volume; we confirm the shipping route and the documents needed before quoting. Sampling 3–7 days, bulk 10–25 days.

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