Guide
Anti-Snap Locks, Lock Snapping and How to Check Your Own Door
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Checking Your Cylinder in Thirty Seconds
The quickest useful test happens on your doorstep: see how far the key cylinder stands out from the handle or escutcheon around it, then read what is printed on its face. Nothing needs unscrewing.
Step one: is it a euro cylinder?
Seen from outside, a euro cylinder's keyhole sits in a rounded top with a slimmer section running beneath. Most uPVC, composite and aluminium doors use one, as do a few timber doors. If you have a mortice lock or nightlatch instead, this check may not fit your door.
Step two: flush or proud
Crouch level with the handle and view the cylinder side-on. It might sit snugly against the plate, stick out noticeably, be recessed too far, be shielded by a security handle or escutcheon, or look damaged or misaligned. Handles and doors vary, so there is no universal projection to measure against.
Step three: the markings
On the cylinder, look for a single star or three, a Diamond symbol, a maker's name or other product details. Then look at the handle on its own, where two stars may appear. Those describe the handle only, so note the two sets apart.
Step four: photographs
Capture the cylinder and outside handle together, a side view, each marking, the inside handle or thumbturn, and the locking strip if the door happens to be open. Such pictures let someone confirm the product without taking the lock apart. Do not force, trim or shift the cylinder, and do not remove hardware looking for marks; the box, receipt or original documents may hold what the face does not.
Reading what you found
- Three stars plus a Kitemark on the cylinder: record the manufacturer and verify that exact cylinder.
- A Diamond mark: look up the exact product in the Sold Secure directory.
- One star on the cylinder, two on the handle: both components and both ratings need verifying.
- “Anti-snap” printed but no recognised mark: the security rating stays unverified.
- Nothing visible: go back to the paperwork or have the cylinder identified.
- Noticeable projection: have its size, fit and protection assessed.
Flush and marked is the good outcome; proud and unmarked deserves attention. “Anti-snap” names an intended design rather than a test result, and this check stops short of proving the complete door is secure. What it gives you is a clear list of what to look at next.
Why the Euro Cylinder Is the Weak Point
The cylinder is the one part of a uPVC or composite door lock that sits on the outside face, within reach of anyone at the door. That exposure is a fixed feature of the euro profile, so the protection has to come from one of two places: a cylinder designed to keep the lock working if its exposed part is damaged, or protective hardware around it. Ratings show which you have.
How TS 007 Stars Share the Job
TS 007 uses stars to rate a door cylinder and the protective handle or cover around it. Because both components can be rated, the number of stars means something different depending on where the marking sits.
| Marking | Where you may find it | What it means |
|---|---|---|
| One star | Cylinder | Needs a two-star handle or protective cover to make up the recognised three-star combination |
| Two stars | Security handle or protective cover | Protects the cylinder and can be paired with a one-star cylinder |
| Three stars | Cylinder | Reaches the three-star level by itself |
There are therefore two routes to the same level. A Kitemarked three-star cylinder gets there without a separate two-star handle for that rating, although the outside handle and correct fitting still matter, and the cylinder's rating says nothing about whether the door, frame or locking mechanism as a whole is secure. Alternatively, a Kitemarked one-star cylinder can be combined with a Kitemarked two-star security handle or protective cover:
One-star cylinder + two-star protective hardware = three-star protection
The stars have to sit on the right components. A handle’s two-star rating does not give the cylinder a two-star rating.
What the Kitemark Adds
The stars should appear with a Kitemark, which shows that the product is covered by the certification scheme. The Kitemark helps show that the product is covered by a recognised testing and certification scheme, and it ought to be accompanied by the correct number of stars. Stars on their own are not enough to go on, because decorative symbols and marketing graphics can look very like official markings. Record the Kitemark, number of stars, manufacturer and product details before verifying the claim. The Door and Hardware Federation’s guidance on TS 007 explains the two recognised ways to reach the three-star level.
The Two Schemes That Mean Something
The two schemes a UK buyer is likely to meet on a cylinder are TS 007, shown as a star rating, and SS 312 Diamond, which Sold Secure publishes. Each is a recognised indicator of cylinder security, each is managed by a separate organisation, and any given cylinder might have one mark, both or none.
TS 007 and Its Star Rating
TS 007 marks come with a Kitemark. A three-star cylinder meets the level on its own, while a one-star cylinder reaches it only alongside a two-star protective handle or surround.
Sold Secure's SS 312 Diamond
Diamond applies to the specific cylinder model Sold Secure tested, and that model should appear in its published directory.
Why fit matters as much as the mark
A security rating tells only part of the story. A well-rated cylinder may protect less if it is incorrectly sized, protrudes unnecessarily or is paired with damaged or unsuitable handles. The distance it extends beyond the outside handle or protective plate is known as cylinder projection, and the cylinder ought to suit the thickness of the door and its fittings. No single projection measurement fits every door, because hardware and cylinder designs differ. One that appears to stick out too far may be easier to grip or attack, but looks alone cannot confirm it is wrongly fitted, which is why accurate measurements are needed before choosing a replacement.
The outside handle or escutcheon (the protective plate around the keyhole) gives another layer. Signs worth noting: - cracks, impact marks or a plate knocked out of position - loose handles, loose fixings or gaps around the cylinder - a cylinder that shifts during normal use
Leave the hardware in place if taking it off would leave the door unsecured. Inside, some cylinders use a key and some a thumbturn; changing between them needs checking first, especially on flat entrances, communal doors and fire doors, where escape and building requirements apply. A loose or wrongly sized cylinder, damaged hardware, a stiff key or thumbturn, an unstable handle or a door that will not lock reliably all call for an inspection. None of these identifies the exact fault, since the key, spindle, multipoint mechanism or door alignment could be responsible, and replacing the cylinder will not correct poor alignment. Treat them as a reason to check the cylinder, handle and locking system together.
Anti-Snap Is a Marketing Word and Not a Standard
Sellers can call cylinders anti-snap without certification. What matters is a mark supported by a certification body's testing of the specific product. Product listings and box descriptions need that supporting evidence before their security claims can be relied upon.
Check Identity Before Interpreting Symbols
A diamond, star or Kitemark may not reveal the exact cylinder rating alone. Visually check both ends, leaving everything assembled. Record maker and model, SS 312 Diamond mark, TS 007 star rating and certification or licence number; photograph illegible details.
TS 007 stars may cover protective furniture as well as cylinders. Locate each mark carefully: neither handle nor cylinder ratings establish the other's rating or whole-door certification.
Compare those identifiers, appearance and ratings against Sold Secure's approved lock-cylinder directory. For police-preferred specification products, Secured by Design's product search offers another check. Seek certification-body records or manufacturer technical confirmation. Missing entries can mean older certification, discontinued stock or another product name. Ask the manufacturer or a qualified locksmith about ambiguity; keep unidentified security ratings unconfirmed.
Understand What Was Tested
Sold Secure expresses SS 312 assessments as grades; stars belong to TS 007. Its recognised door-cylinder rating, SS 312 Diamond, is awarded through Sold Secure after that exact model passes testing. Diamond currently leads the cylinder directory's grades. Some cylinders have this and TS 007 three-star, but the ratings are independent.
Sizing and installation still need checking with SS 312 Diamond. That award does not certify the handle or cover, establish multipoint condition or settle insurance requirements for the door. Suitable hardware remains necessary.
What Upgrading Actually Involves
On most uPVC and composite doors, upgrading means swapping the cylinder, which is held by a single fixing screw. It is not a new door and not a new mechanism: a euro cylinder is normally a separate component, so it can usually be changed without replacing the multipoint lock. That fits the term, since “anti-snap” describes protection in or around the cylinder rather than the locking mechanism inside the door.
Changes
the cylinder, replaced by a rated one sized so it sits close to the handle.
Stays
the multipoint mechanism and the door itself.
Stays unless upgraded
the handle, which can remain if it is secure, undamaged and compatible with the new cylinder.
What changes and what does not
A cylinder-only change suits a lost, stolen or possibly copied key, a worn or damaged cylinder, one an undamaged key no longer works reliably, a wrong-sized cylinder, or a wish to move to a verified rated cylinder, provided the handle and multipoint mechanism still work properly. A cylinder that moves is not always the culprit; a loose retaining screw or damaged handle can cause it, so confirm the cause before buying anything.
Measure before you purchase. The replacement has to match the door and its hardware, euro cylinders are measured from the centre of the fixing-screw position to each end, and the inside and outside lengths may differ. It also needs the right inside operation, a key or a thumbturn. On a flat entrance, communal entrance or fire door, the new cylinder must keep the doorset suitable for its escape requirements.
A new cylinder will not help if the handle no longer drives the locking points, hooks, rollers or bolts are stuck, the door has dropped, the gearbox has failed, the handle or plate is damaged, or the door stays insecure while the key turns. Those need adjustment, hardware repair or mechanism work. A damaged or unsuitable handle can weaken a rated cylinder, and some recognised arrangements depend on a protective handle or escutcheon, so look at the cylinder, handle and lock as one system.
What Else Is Worth Doing to the Same Door
Treat the door as a system rather than a single lock. A good anti-snap cylinder improves one vulnerable part, but the protection it gives depends on the handle, multipoint mechanism, hinges, frame and door around it, and a weak spot in any of them can cut into the benefit of a highly rated cylinder.
Handle and escutcheon
the plate covers the cylinder, and a rated handle is one of the two ways to reach three stars.
Keeps and alignment
a door that needs lifting, pushing or pulling to close, or locking points that need force on the key or handle, is not fully protected by anything fitted to it.
Hinges, frame and its fixings
a door that has dropped or a frame that moves weakens the lock's position.
Nearby glazing
a glazed panel close to a thumbturn deserves a mention.
Four places to look next
Ratings are specific. A TS 007 or SS 312 rating applies to the product that was tested, not automatically to the complete door, frame or locking system. A three-star cylinder may offer strong protection against attacks aimed at it, but it cannot compensate for a damaged handle, loose frame, failed multipoint mechanism or poorly fitted door. A doorset tested and certified as a complete system is a separate category from an existing door with a rated cylinder added.
The right cylinder can still under-perform when it is the wrong length, stands out past the handle without need, is loose within the mechanism, is fitted beside damaged or unsuitable hardware, or is in a door that does not close or lock correctly. Should you do one thing only, make it the cylinder, then work outwards: rating, size, installation and hardware all have to work together.
Ask Us What Your Cylinder Is
Tell us what is on your door and Big Locksmiths Boston will read the markings, explain what the cylinder is, and price a change if you decide 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. A label on its own is not enough, so the markings and the exact product come first.
When it is worth asking
Get in touch if you cannot verify the rating, the cylinder has no identifiable maker or mark, it projects noticeably, the cylinder or handle moves in use, the key sticks or only works at certain angles, the handle does not throw every locking point, the door works open but stiffens when closed, the door has dropped, the handle, escutcheon or frame is damaged, a key is lost, stolen or possibly copied, or the door has been affected by an attempted break-in. If the door cannot currently be locked, say so when you call.
What we look at
The cylinder's type, size and condition and any certification marks; the handle or protective plate; whether the multipoint mechanism works and how the locking points meet the frame; whether the door or hinges need adjusting; and whether a new cylinder alone would fix the problem. Ask which component needs attention and why, and whether the answer is adjustment, a cylinder upgrade, protective hardware or work on the wider mechanism, because the handle, mechanism, hinges, frame and alignment matter as much as the cylinder.
Have ready: the door material, a photo of the cylinder face and body, whether it sits flush or proud, any markings, photos of the handles and door edge, and what you have noticed.
There is no call-out charge at any hour, emergency calls are answered 24 hours a day, every day of the year, and the price is given on the call from what you describe.
Ask What Cylinder You Have: 01205 601044
Prefer to send photos first? Call or message Big Locksmiths Boston.
Anti-Snap Lock Questions
How can I tell if my door lock is anti-snap?
Use the cylinder’s recognised rating to judge its anti-snap credentials. A TS 007 three-star Kitemark is one example; SS 312 Diamond certification is another. Simply finding the phrase “anti-snap” does not tell you whether an independent body has tested the cylinder.
Does a TS 007 three-star cylinder mean it is anti-snap?
Yes, a verified three-star TS 007 cylinder has tested resistance to snapping. The testing also covers other recognised ways of attacking it. For identification, the appropriate Kitemark should appear on the cylinder together with three stars, matching the rating being claimed.
Is SS 312 Diamond better than TS 007 three-star?
No rating is universally superior on its name alone. SS 312 Diamond and TS 007 three-star belong to separate certification systems with different testing requirements. Stars identify levels within TS 007, while SS 312 uses Sold Secure grades. Each rating covers the exact product tested, and holding one does not establish the other. Some cylinders have both. Either certification indicates enhanced cylinder security and offers firmer evidence than an unsupported “anti-snap” description.
Can I replace the euro cylinder in my uPVC door with an anti-snap cylinder?
Yes, an anti-snap replacement is possible in many cases. The cylinder must match the euro-profile design, fit the required measurements on both the inside and outside, and provide the right operating arrangement. Compatibility with the hardware already fitted to the door is also essential.
Do I need new handles with an anti-snap cylinder?
The handles only need changing if they cannot meet the required condition and compatibility checks. Undamaged, secure handles that suit the new cylinder can remain. A replacement cylinder is feasible in many cases; it must have the correct euro-profile shape, external and internal dimensions, operating arrangement and compatibility with fitted hardware. Some recognised security arrangements rely on combining a cylinder rated one star with two-star protective handles or with a lock surround.
What if my cylinder has stars but no Kitemark?
The three-star TS 007 rating remains unverified from stars alone when the associated Kitemark is absent. Take a complete note of the markings and check the precise product model and manufacturer in an official product record. A star count is not sufficient confirmation.
Does an anti-snap cylinder stop every type of break-in?
No, fitting an anti-snap cylinder cannot cover all possible routes of entry. Its design addresses attacks directed at the cylinder. Security is also influenced by how well the door is installed and by its multipoint lock, handle, glazing, hinges and frame.
Why does my lock work with the door open but not when closed?
The locking points, or the door as a whole, could be out of line with the frame. Start by checking the hinges, keeps, latch and bolts. These checks belong before cylinder replacement, because a different cylinder cannot remedy the underlying alignment problem.
Should I replace the cylinder after losing a key?
Consider having the cylinder replaced promptly if someone could connect the missing key with your property, or if it might have been copied. A change stops that lost key from operating the door, removing its continued use in that lock.
How often should an anti-snap cylinder be replaced?
There is no standard period after which every anti-snap cylinder must be replaced. Instead, organise an inspection or replacement when it is damaged, poorly fitted, unreliable or affected by an attempted attack. Take the same step if your security needs now require something different.