The short answer
A mechanical seal is cheap and single-use. It meets standards and security programmes, but you only learn about tampering at unloading. An electronic seal is a reusable device. It reports opening, cable cutting and the cargo position in real time. For high-value cargo the two are often used together.
Mechanical seals and ISO 17712
Mechanical seals for containers and trailers are covered by ISO 17712:2013 “Freight containers – Mechanical seals”. It is the current edition and replaced the 2010 version. The standard sorts seals into three classes by strength:
- I (indicative) – e.g. plastic seals. They can be broken by hand or with scissors and only show that the doors were opened.
- S (security) – removing them requires simple tools.
- H (high security) – e.g. bolt and cable seals. They can only be removed with bolt or cable cutters.
The class is confirmed by tests in an independent laboratory accredited to ISO/IEC 17025. An H-class seal is marked “H”. The US C-TPAT programme requires ISO 17712 high-security seals on all loaded containers bound for the United States.
Electronic seals
An electronic seal combines a mechanical closure (bolt, steel cable or shackle) with electronics. There are two types:
- RFID seals under ISO 18185. This 2007 series describes electronic container seals read by readers at 433 MHz and 2.45 GHz. You only get information when the container passes a reader, e.g. in a port.
- GPS seals with cellular or satellite connectivity. They send data to an online platform themselves: position, opening, cable cut, battery status. STARCONT supplies this type.
A GPS seal works along the whole route. You can set geofences – areas where it may be opened – and get an alarm if someone tries elsewhere. Opening requires authorisation, e.g. an RFID card, an SMS or a command from the app. Every event is logged with date and place.
Comparison
| Feature | Mechanical seal | Electronic GPS seal |
|---|---|---|
| When you detect tampering | At inspection or unloading | Immediately – alarm on the platform and phone |
| Place and time of the event | Unknown | GPS position and time of every opening |
| Use | Single-use | Reusable, rechargeable battery or solar panel |
| Who can open it | Anyone with a tool | RFID card, SMS, app, remote command |
| Standard | ISO 17712 (classes I, S, H) | ISO 18185 for RFID seals; GPS seals – device certificates (e.g. E-mark, ATEX) |
| Cost | Low per piece, paid on every trip | Higher up front, then a data subscription |
What TAPA TSR 2026 says
The TAPA TSR 2026 standard for carriers of high-value cargo has applied since 15 September 2026. At every certification level it requires seals certified to ISO 17712 (class I, S or H) on all direct, non-stop shipments. The carrier needs a procedure defining who applies and removes seals; the driver may not do it without the buyer's exemption. At the top level, TSR 1, unauthorised opening of cargo doors must also send a signal to the alarm monitoring centre – exactly what an electronic seal or sensor provides.
When to choose which seal
A mechanical seal is enough when the cargo is low-value, the route is short and well known, and the shipper only needs proof of integrity at delivery.
An electronic seal pays off when:
- you carry valuable or theft-targeted goods such as electronics, pharmaceuticals, metals or fuel,
- the route is long, crosses several countries or includes stops at unsecured parking,
- you want to decide remotely who may open the cargo and where,
- you need evidence with date and place, e.g. for an insurer or a dispute,
- you work in explosive atmospheres and need an ATEX-certified device.
Examples of STARCONT electronic seals
- AT-16 Mini – compact 2G/4G GPS seal with cable for containers and trailers; opened by RFID card or SMS, cable-cut alarm.
- G-508N – ATEX-certified seal with a 14,400 mAh battery, geofences and route replay; for tankers and trailers.
- AT10G – seal with Iridium satellite and 4G connectivity and a solar panel, for routes without GSM coverage.
- G-508V – seal with a camera that documents every opening with a photo.
See the full list in the electronic seals category.