Plastic sealscan be split into two main groups: single use and reusable. Single use seals are typically made of plastic or metal, and the used material and production technology is the key to their security level. Reusable seals are usually electronic or mechanical rather than just made from plastic, and if purely plastic, only one part is reusable. A reusable mechanical or electronic seal can be fitted to the rear or loading doors, extending a cable from itself through fixing points on the doors, and when sealed generating a unique number which is logged. When the door is next opened this number changes, so it provides tamper evidence for the load.

The requirements for certain security level of seals are defined in the ISO PAS 17712. The seals that belong to the High security level and Security level are also called "barrier seals". They are made of different metals or metal alloys, meaning that they require special tools to be opened, such as bolt cutters or pliers. Cable seals and plastic seals also fall into this category. Designed to deter opportunistic theft of high value goods, they also can often be branded and numbered to improve tamper resistance and provide excellent security for containers.

The seals that are in the Indicative level as to ISO PAS 17712 are made of plastic or thin metal. Bolt seals are used to secure shipping containers, trucks and trailers. A bolt seal used for securing containers must conform to the ISO 17712 high security seal in order to be accepted by customs all around the world in ocean shipping. Bolt seals are generally closed by hand and opened with the use of bolt cutters. These gives a strong and secure plastic seals for transportation, while remaining convenient for staff in ports and warehouses. All ISO 17712 compliant seals are numbered on both seal body and head, to prevent substitution of either part. This is usually done using laser marking, which cannot be rubbed off.