Locks explained
Anti-Snap Cylinders: TS 007 3 Star and SS 312 Diamond
An anti-snap cylinder is a euro cylinder built and tested to resist snapping. Look for TS 007 3 star, a 1 star cylinder paired with a 2 star handle, or Sold Secure SS 312 Diamond. Insurers often expect one on uPVC and composite doors. Fitted, an anti-snap cylinder costs £137 to £150 (MLA price list; Checkatrade).
What is cylinder snapping?
Cylinder snapping is a burglary method that breaks a weak euro cylinder at its narrowest point so the lock can be worked from outside. Standard cylinders are vulnerable because they are thin in the middle, where the fixing screw passes. This site does not describe how it is done. What matters for a householder is that a graded cylinder is designed and tested to resist it, and that the grade is marked on the cylinder itself. It mainly concerns uPVC and composite doors, and timber doors fitted with euro-profile locks, because all of them use the same kind of cylinder.
What does TS 007 3 star mean?
TS 007 is a BSI Kitemark scheme for euro cylinders and door handles. Products are rated in stars, and the protection adds up:
- A 3 star cylinder resists snapping on its own, whatever handle it sits behind. - A 1 star cylinder with a 2 star handle gives the same combined rating, because the handle guards the cylinder. - A 1 star cylinder on its own meets the basic test but is not the snap-resistant grade.
Look for the Kitemark with three stars on the face of the cylinder, or a 1 star mark with a matching 2 star handle. Stars printed only on the packaging are not enough; they should be on the part.
What does SS 312 Diamond mean?
SS 312 is Sold Secure's test standard for euro cylinders, and Diamond is its top grade, covering resistance to snapping among other attacks. A Diamond cylinder is marked on its face. Sold Secure is owned by the Master Locksmiths Association and tests and grades products; it does not assess the people who fit them. Insurers commonly list SS 312 Diamond and TS 007 3 star side by side as acceptable on uPVC and composite doors, though each policy has its own wording. Many cylinders carry both marks.
How can you tell if your cylinder is anti-snap?
Open the door and look at the face of the cylinder, the end you put the key in. A Kitemark with three stars, a 1 star Kitemark backed by a 2 star handle, or the words SS 312 Diamond mean it is graded. If there is no mark at all, assume it is a standard cylinder. A cylinder that sticks out a long way past the handle is a further warning, whatever its grade. The invoice from your last lock change, if it names the standard, is useful evidence to keep for your insurer.
What does an upgrade cost, and when should you call a locksmith?
An anti-snap cylinder costs £137 to £150 fitted (MLA price list; Checkatrade, checked October 2026), against £105 to £175 for a cylinder change in general (MLA price list; MyJobQuote). Most upgrades are a straight swap, sized to your door so the cylinder sits close to flush. Call a locksmith to fit one after a break-in, when you move house, or when your insurer names a grade. Ask for the standard to be written on the invoice, and keep the spare keys and any key card together.
Common questions
Is TS 007 3 star better than SS 312 Diamond?
They are separate schemes, one run by BSI and one by Sold Secure, and both are treated as snap-resistant grades. Many cylinders carry both marks. Check which your insurer names, if it names one.
Do I need an anti-snap handle as well?
Not with a 3 star or Diamond cylinder, which resist snapping on their own. A 2 star handle is what lifts a 1 star cylinder to the same combined rating.
Will an anti-snap cylinder fit my existing door?
Almost always. Euro cylinders share one profile, so a graded cylinder of the right length replaces a standard one without changing the mechanism. Measure, or let the locksmith measure, before ordering.
How do I know a locksmith fitted a genuine graded cylinder?
Check the mark on the cylinder face before they leave, and ask for the standard and the cylinder's make on the invoice. Keep the key registration card if one comes with the cylinder.