Guide
Anti-Snap Locks, Lock Snapping and How to Check Your Own Door
Start at your own front door: if the cylinder on a uPVC or composite door stands out beyond the handle, that is the part worth a closer look. Lock snapping is aimed at the euro cylinder, the replaceable barrel the key slides into, and the exposed portion is what matters.
Seeing "anti-snap" on a product listing tells you what a cylinder is meant to resist, not how it was tested. It is a description rather than a certification. Two schemes do carry real weight in the UK, and both leave a mark on the cylinder itself. This guide from Runcorn Locksmith shows you where to find them and what they mean. To have someone look for you, call 01928 611001. Calls are answered around the clock, every day of the year, across Runcorn.
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Check Your Cylinder in Thirty Seconds
Look at the keyhole side of your door from outside and note how far the cylinder pokes out past the handle or the escutcheon that surrounds it. Many uPVC, composite and aluminium doors use replaceable euro cylinders; this check applies to those cylinders.
The four-step check
- Go outside, pull the door shut and stand facing the side with the keyhole.
- See whether the cylinder sits level with the handle plate or stands proud of it.
- If it stands proud, measure the overhang with a ruler or tape. The Crime Prevention Website notes that on some doors a cylinder can stick out from the face of the door by as much as 10mm.
- Look closely at the face and the body of the cylinder for a star symbol or a diamond symbol. A mark like that is the only certification evidence the part itself can give you. If you are not sure what kind of lock you are looking at, our guide to how to tell which lock type you have will help.
Reading the result
- Flush, and carrying a mark: the cylinder is in good shape on both counts.
- Proud, and carrying no mark: this is the combination worth acting on.
Two marks deserve a follow-up. Where you find three stars together with a Kitemark, write down the manufacturer and confirm the exact cylinder model. Where you find a Diamond symbol, look the exact product up in the Sold Secure directory. A security handle or protective plate around the cylinder adds a layer of its own. Leave everything in place while you check. For help with the hardware itself, see our page on uPVC and composite door lock work.
Why the Euro Cylinder Is the Weak Point
The metal in the middle of a euro cylinder, below the cam, is thin, and the Crime Prevention Website describes that as the weak point. Because it is built into the profile, no manufacturer can design it away. The answer is either a cylinder engineered to fail safely at that spot, or hardware that keeps the cylinder from being reached at all.
Where the Weakness Sits in the Cylinder
The euro profile narrows at its centre, around the cam that throws the lock, and that narrowing belongs to the shape rather than to any manufacturing defect. A cylinder built to deal with it is what you are really paying for, and it generally does three things:
- It includes a sacrificial section, designed to break at a planned point so that the part left in the door still works the lock.
- It carries hardened inserts and pins inside the body to resist drilling.
- It uses pin designs that guard against other approaches, which is why certification tests a cylinder against several threats rather than just one.
This is why two cylinders that look the same on a shelf can be priced very differently, and why the marking tells you more than the wording. If you are weighing up having a cylinder replaced, ask about the marking before anything else.
Why This Is a uPVC and Composite Door Subject
To be straightforward about scope: this is a euro cylinder issue, so it concerns uPVC, composite and aluminium doors and largely passes by a timber door secured with a mortice lock. A mortice lock has no euro cylinder, so the question never arises; timber door security is judged against a different standard. Because uPVC and composite doors are fitted to a large share of UK homes, this is an everyday question, not a specialist one.
- Applies: uPVC, composite and aluminium doors fitted with a euro cylinder.
- Largely does not apply: timber doors secured by a mortice lock.
The section on the two recognised schemes below explains which marks to look for.
That second answer explains why the ratings look beyond the cylinder. TS 007 awards stars both to a door cylinder and to the protective handle or cover around it, so a star count only makes sense once you know which part it sits on:
| Marking | Where it appears | What it tells you |
|---|---|---|
| One star | On the cylinder | Reaches the recognised three-star combination only when paired with a two-star handle or protective cover |
| Two stars | On a security handle or protective cover | Shields the cylinder and can be teamed with a one-star cylinder |
| Three stars | On the cylinder | Reaches the three-star level without any help |
Whatever the count, the stars should sit alongside a Kitemark. The Kitemark is the sign that the product falls within a recognised testing and certification scheme. Before you rely on any claim, note the Kitemark, how many stars there are, the manufacturer and the product details, so the claim can be checked.
Anti-Snap Is a Marketing Word, Not a Standard
Any seller may describe a cylinder as anti-snap, because the phrase is a description and not a certification. The same is true of "snap-resistant" and "high-security": unless a recognised rating stands behind them, they are product copy. The claim worth trusting is a mark on the product itself, applied after testing by a certification body, and everything else is marketing. That habit of asking for evidence is just as useful when you check what a tradesperson is actually claiming.
The Features Behind the Phrase
"Anti-snap" generally gathers several separate features under one label. Designs differ between products, but you may come across:
- A sacrificial section, made to break at a controlled point.
- Anti-drill inserts, hardened parts that resist drilling.
- Anti-pick pin designs, which defend the pins inside.
- Anti-bump measures, which address a different approach altogether.
A cylinder with one of these may be sold as anti-snap just as readily as a certified one with all four, and the listings can read the same. The question to put to a seller or a locksmith is simple: which of these features does this cylinder have, and what certification does it carry?
What a Listing Does and Does Not Prove
Treat a product title as a claim and a mark on the cylinder as evidence. When reading a listing:
- Look beyond the words "anti-snap" and see whether a scheme and a rating are actually named.
- Work out whether that rating belongs to the cylinder or to a handle sold alongside it.
- Check whether the marking is described as Kitemarked.
One trap is worth naming. A listing can pair a two-star handle with a cylinder that has no certification of its own, and the star figure in the headline then belongs to the handle, not to the barrel. Ask for the certification mark that will be on the product you actually receive, rather than relying on the description on screen. If cost is part of the decision, our guide to what lock work costs in Runcorn explains what drives it.
The Two Schemes That Do Mean Something
The two marks to recognise are TS 007, which uses a star rating, and SS 312 Diamond, published by Sold Secure. Both are recognised marks of cylinder security, they are run by different organisations, and a given cylinder may carry one, both or neither. The Crime Prevention Website's advice is to replace a vulnerable cylinder with a BSI Kitemarked or SS 312 cylinder that resists bumping and snapping, together with the door handle or other protective hardware. For how these sit beside other standards and insurer wording, read what BS 3621, TS 007 and insurance approved really mean.
TS 007 and the Star Rating
In one line: TS 007 is the cylinder and door hardware specification developed by Secured by Design with the Door and Hardware Federation and the Glass and Glazing Federation, and it grades products in stars. The detail that affects what you buy is that three stars can be reached in two ways. The scheme rates the assembled defence, because a cylinder can be reached through the handle and the escutcheon as well as directly.
- Route one: a TS 007 three-star cylinder used on its own.
- Route two: a TS 007 Kitemarked one-star cylinder combined with a TS 007 two-star Kitemarked armoured handle or lock surround.
For route two to count, both parts have to be TS 007 rated and Kitemarked. The Door and Hardware Federation's guidance on TS 007 sets out both routes to the three-star level. Once verified, a TS 007 three-star cylinder has been tested to resist snapping as well as other recognised attack methods, and the cylinder should display the relevant Kitemark together with three stars. If the answer for your door is new hardware, see our page on.
SS 312 Diamond and Sold Secure
Put plainly, SS 312 Diamond is a cylinder security standard published by Sold Secure, and it is the second mark a UK buyer is likely to meet. It is awarded through Sold Secure only after the exact cylinder model passes the required tests, and Diamond is currently the highest cylinder rating shown in the Sold Secure directory. Because this is an independent scheme with its own testing, a Diamond cylinder has been assessed against that standard rather than against TS 007. Some cylinders carry both marks and some carry one. Different test requirements underpin these separate certification systems, so their names alone do not establish which is better.
What to look for:
- A Diamond symbol on the face or body of the cylinder, in the same place a star rating would appear.
- The complete marking, so the exact manufacturer and model can be checked against an official product record.
Bear in mind that three stars without the relevant Kitemark are not enough to verify a TS 007 three-star rating. The practical rule is that a mark from either scheme means something, and no mark does not.
Assessing the cylinder means looking beyond its rating. Even a top-rated cylinder can protect less than it should if it is the wrong size, overhangs for no reason, or sits in damaged or unsuitable door furniture. Check how far it reaches beyond the outside handle or protective plate, which is sometimes called cylinder projection, and make sure it has been sized to the thickness of the door and its hardware. There is no single projection figure that suits every door, since handles, plates and cylinder designs all differ.
What Upgrading Actually Involves
For most uPVC and composite doors, an upgrade means swapping the cylinder: one fixing screw and a modest job, not a new door and not a new mechanism. A euro cylinder is usually a separate component, so it can commonly be changed without replacing the whole multipoint lock. "Anti-snap" describes protection built into or placed around the cylinder; it says nothing about the locking mechanism inside the door.
What changes
the old cylinder comes out and a rated one goes in, sized so it sits flush instead of proud.
What stays
the multipoint mechanism, the door and, unless they are being upgraded too, the handles, as long as they are secure, undamaged and compatible with the new cylinder.
What comes first
the replacement must match the euro-profile design, the door's thickness and the existing measurements, so measuring happens before buying. Our guide to how a replacement lock is measured and fitted covers that step.
A cylinder-only change can also be the right move when a key has been lost or stolen or might have been copied, or when the cylinder itself is worn or damaged. The honest limit is this: a rated cylinder in a door whose mechanism is failing still leaves you with a failing mechanism, and those are two separate jobs.
What Else Is Worth Doing on the Same Door
The cylinder is one part of the door's defence, and the hardware around it does the rest. An anti-snap cylinder can strengthen one vulnerable component, but it cannot make the whole door secure by itself, because it works as part of a system that includes the handle, the multipoint mechanism, the hinges, the frame and the door leaf. A weakness anywhere in that system can reduce what even a highly rated cylinder provides, so the door is best judged as a whole. These are the parts worth a look:
The handle and escutcheon.
A rated handle is one of the two routes to a three-star result, and it shields the cylinder.
The keeps and alignment.
A door that does not close properly is not protected by anything fitted to it.
The hinges,
especially on a door that opens outwards.
Glazing beside the door,
since a thumbturn within reach of a glass panel changes the picture.
It also helps to remember that a TS 007 or SS 312 rating applies to the product that was tested, not to the door it is fitted in. If you are only doing one thing, start with the cylinder: it is the simplest change with the clearest effect.
Ask Us What Your Cylinder Is
Send us the details and we will read the markings on the cylinder you have, tell you what it is and quote for a change if you want one. An anti-snap cylinder is worth considering when it has a verified TS 007 or SS 312 rating, fits the door correctly and works with suitable protective hardware. An inspection makes sense when you cannot confirm the rating, the lock has become unreliable or the door will not secure properly. Typical signs:
- No identifiable rating or manufacturer on the cylinder.
- Noticeable overhang where the cylinder extends past the outside handle.
- Movement in the cylinder or handle when the lock is used normally.
- Sticking or difficulty turning the key, or needing to hold it at certain angles for it to work.
Have ready: the door material, a photograph of the cylinder face and body, and whether it sits flush or proud.
There is no call-out charge at any hour, and emergency calls are taken 24 hours a day, every day of the year. Technicians are [PROVIDER PACK: DBS check confirmation] and the business holds [PROVIDER PACK: public liability insurance details]. Each job is priced on the call from what you tell us, and if anything found on site would change that price, you hear about it before work begins. [PROVIDER PACK: whether TS 007 or SS 312 rated cylinders are stocked and fitted as standard]
Ask What Cylinder You Have: call 01928 611001.
Anti-Snap Lock Questions
What does anti-snap actually mean?
If someone attempts to break the exposed section, an anti-snap cylinder is designed to help protect the lock. How the product was tested cannot be established from that label; it identifies an intended feature. Designs vary, though many include a section made to break in a controlled position.
Is an anti-snap lock the same as a three-star lock?
The two terms are not interchangeable: calling a cylinder "anti-snap" provides no confirmation of independent testing. Three stars is a TS 007 rating, and it only counts when the matching Kitemark appears with it. Look for a recognised rating, such as a TS 007 three-star Kitemark or SS 312 Diamond certification, rather than the phrase.
Are SS 312 Diamond and TS 007 three-star the same rating?
No. SS 312 Diamond and TS 007 three-star are separate ratings, run as separate schemes. Both apply to the exact product that was tested, and holding one does not automatically prove a cylinder has the other. Never assume that every three-star cylinder is also Diamond rated, or the reverse; check each claim against the exact manufacturer and model. Either gives stronger evidence than the word anti-snap, and some products carry both.
My home insurance mentions a standard. Which one applies to my door?
Policy wording varies. Some policies ask for approved locks, while others may refer to a specific British Standard, a multipoint locking system or minimum-security precautions. The references you are most likely to see are BS 3621 for certain key-operated locks, TS 007 for replaceable cylinders and protective hardware, and SS 312 Diamond for security cylinders. These standards apply to different products and door arrangements, so read your own policy and see our guide to BS 3621, TS 007 and insurer wording.
Can I keep my existing handles when I change the cylinder?
In many cases you can. Compatibility with the existing door hardware is essential. Check that the replacement's euro-profile design, measurements on both the internal and external sides, and operating arrangement are correct. Handles can stay if they are secure, undamaged and compatible. For some recognised arrangements, two-star protective handles or a lock surround must accompany a one-star cylinder.
Does an anti-snap cylinder stop every kind of break-in?
No. A rated cylinder is built to resist attacks aimed at the cylinder, but it cannot guard against every way into a home. The handle, mechanism, hinges, frame and door all play a part.