# Trailer security seals

*Last updated: 2026-06-26*

> When a trailer leaves the loading dock under seal, the security seal becomes the chain of custody's critical link.

When a trailer leaves the loading dock under seal, the security seal becomes the chain of custody's critical link. Trailer security seals are tamper-evident devices – made of plastic or metal – fitted to the door locking mechanism; any forcible removal or bypass leaves visible, irreversible marks that cannot be concealed. Customs authorities worldwide accept properly affixed seals as evidence that a consignment has not been interfered with in transit; a missing or damaged seal typically triggers a more thorough physical examination. Each seal carries a unique serial number entered in the shipping documents, enabling full traceability from origin to destination. Conventional seals are passive by nature: they record unauthorized access after the fact rather than actively preventing it, which sets them apart from electronic seals (e-seals) capable of sending real-time alerts. In day-to-day freight operations, seal numbers are a mandatory entry on the CMR consignment note and the customs declaration.

**Source:** [https://en.wikipedia.org/wiki/Security_seal](https://en.wikipedia.org/wiki/Security_seal)

## Quick Facts

| Property | Value |
|---|---|
| Term | Trailer security seals |
| Language | EN |
| Word count | 151 |
| Last updated | 2026-06-26 |
| Source | https://en.wikipedia.org/wiki/Security_seal |

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