Picture of Choosing the Best Security Seal for the Job

Choosing the Best Security Seal for the Job

With the range and breadth of security seals on the market, it can be very challenging for the uninitiated to know which seal to choose to best suit their needs. From the outset, it is recommended that the decision-maker considers the purpose of the security seal in relation to the application. Considering some of the fundamentals from the outset will help to select the right seal for the job…

…why is the user sealing the enclosure in the first place? Is it for loss prevention, safety purposes, product integrity, brand assurance...?

…what type of goods will be protected? What is the value of the goods?

…where is the seal going, and how? Cross-border shipments are subject to customs regulations which will affect the seals that can be used

…what kind of resistance is required? What are the consequences should if the security seal has been broken or tampered with?

…what environment is the seal being used in? What is the operating temperature? How long does the seal need to last for?

Answers to these questions will have a bearing on the material, form, shape, strength of the most appropriate security seal.

It should also be noted that a security seal alone cannot provide an iron-clad guarantee of integrity. No manufacturer anywhere in the world can say with complete certainty that – given enough time, appropriate circumstances, resources, skills and ingenuity – their security seals are undefeatable... but this is also true of safes, door looks, padlocks and alarms. Security seals should always be used as one layer within an ‘onion skin’ of security (view our guide to security protocols).

With this said, below we note some key characteristics of seals you should consider when choosing the most suitable. Try out our handy filtering tools shown on our main security seals category to find a product matching your needs.

Seal FeatureConsiderations
Design Type

Seals come in many forms... Pull-through Security Seals, Fixed-Length Security Seals, Security Padlock Seals, Barrier Seals (Cable Seals and Bolt Seals), Wire/Rope Meter Seals, and even Reuseable Electronic Seals. Security seals also include security tapes and labels, suitable for flat surfaces and edges on enclosures such as crates, cartons and pallets. Each type is designed for particular types of applications - for more information, see types of security seals.

Physical Fit (Diameter, Length and Flag Size)

Each security seal will have a particular tail or hasp diameter, an effective useable length, and a standard flag size for visibility of printed identification markings. Narrower seals are useful where seals must fit into smaller apertures, and for this many of our pull-through seals have smaller diameters, such as the MiniLock 570's 1.4mm tail thickness and UniTite 414's 2mm thickness. We also offer extra long seals, such as the UniStrap 412-XL (overall 51cm length) and UniTite 413 (overall 49cm length). In terms of flag size ("marking area"), we offer specialised security seals such as our UniFlag Security seal, which has a large format (108x56mm size). 


Common materials in use for security seals are polypropylene, nylon, aluminium and steel. Polypropylene is a popular choice for pull-through seals, as it offers a combination of strength, flexibility and wide operating temperatures. However, all types of plastic do become brittle at increasingly low temperatures, and do degrade when exposed to UV light, long-term saltwater exposure, solvents etc. Metal aluminium and galvanised steel cable seals provide more durability and strength where circumstances dictate, and we can also specify stainless steel cable grades for most demanding applications: see our Flexigrip 150M and Flexigrip 325M models.


Seals are specified for particular strengths – for certain applications such as fire extinguishers, kit bags and first aid trolleys it is desirable to have a very low break-strength so that seals can be broken in an emergency – for others, for example mail sack security seals, it is important that seals with strong break strengths are used so that bags do not burst open when under tension. There is a wide range of tensile strengths available, from 5KgF all the way up to 2000KgF, so understanding the possible forces relevant for your application is important for specifying the right kind of seal.

Level of Tamper-Evidence

We categorise our security seals as having either a Low, Medium or High degree of tamper-evidence, based on design and construction features, method and material of construction, and level of certification.

ISO Classification

Linked to the above, higher levels of security seals are often required for international freight movements - in particular, High Security Seals as classified under ISO17712:2013 regulations for international shipping container and freight movements.

Removal Method

Some applications require easy-access into a sealed enclosure, and for this we have security seals that can be removed easily by hand, either with low-break strengths (see our Fireseals) or tear-line features (see our Tracewaste Tear-Off and UniStrap 412LT).

For other requirements, security seals need to be robust and should not be removed intentionally without simple tools such as scissors or tin-snips, such as our UniTite 413.

In other scenarios, particular for barrier seals, we have our heavy-duty cable and bolt seals, products such as our Flexigrip 325MFlexigrip 500M and Fork seals which necessitate the use of heavy-duty cutting tools like bolt croppers to remove.


Sustainability should of course be at the heart of every business, and security seals should be no exception. All of our plastic security seals are 100% recyclable, and we are increasing options for recycled content and biodegradable security seals on a regular basis.

Universeal UK has been supplying security seals since 1992, and we are one of the leading organisations in the industry. Please email [email protected] for more information on our range and how we can assist. For advice on using security seals within a wider security program, please continue reading our next article in the series, Security Protocols: Making Security Seals work for You.

This article is the second of four, looking at how security seals can fit within your wider security protocols. View Series below...

  1.        What are Security Seals?
  2.        Choosing the Best Security Seal for the Job
  3.        Security Protocols: Making Security Seals work for you
  4.        Glossary – Understanding security seal terminology