Padlock seals are usually supplied as a completely plastic seal, shaped as a standard padlock would be. Technically, they can be classed as a fixed length seal. They feature the same types of tamper-evident protection 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 metal padlock would 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.