Fixed length plastic seals tend to be more tamper resistant than variable length as there are no sliding parts, they simply 'click' into place to lock, which can make them easier to fit than variable length seals. Most fixed length seals can also be branded and numbered for extra security. Fixed length is often the choice of single use security seals for transport applications.

Padlock plastic seals are usually supplied as a completely plastic seal, shaped as a standardpadlockwould be. Technically, they can be classed as a fixed length seal. They feature the same types oftamper-evidentprotection as variable length and fixed length have available - numbering, bar-coding and branding - but fit some different applications. The most common use for these seals is for airline duty free trolleys. One reason for this is that plastic padlocks can be placed over a locking part as any metalpadlockwould be to secure, but do not require keys to open, they simply break off at their built in break point using hands or a small pair of wire cutters. They are secure due to the audit trail available as a result of the sequential numbering.

Meter plastic seals are used with electric or gas or water meters and usually molded in polycarbonate. The transparent body of the seal means that the locking mechanism is visible, and can provide clear indication of tampering. Meter plastic seals can withstand exposure to sunlight and extreme weather, and a wide range of temperatures. Designed for only a single use, they are destroyed when removed. Some meter seals contain components which glow underlight, allowing the seal to be easily located in darkness.