Variable length seals are commonly known as "pull tight seals". This offers an instruction to the user, as a loose pull tight seal provides the opportunity of tampering to the dishonest employee. Pull tight security seals should be used on applications that do not flex excessively in transit or if they do, the tension exerted is insufficient to break the seal. Choice of material is important too depending upon your application.
Visit the Unisto Ltd website for more information on Pull Tight Seals