Anti-Snap Locks: What They Are and Whether You Need One
Cylinder snapping is the most common forced entry method in the UK. An anti-snap cylinder stops it. Here is what to look for and whether your door is already protected.
## The attack takes about 20 seconds
Cylinder snapping requires no skill and no specialist tools. The attacker grips the part of the euro cylinder that protrudes from the door face — a few millimetres on most standard installations — with a pair of pliers or a hammer and screwdriver. They apply force until the cylinder snaps.
On a standard cylinder, this exposes the internal cam. The cam is what your key turns to retract the bolt. Once exposed, it can be turned with a flathead screwdriver. Door open.
This is the most common forced entry method on UPVC and aluminium doors in the UK. It leaves minimal noise, minimal visible damage, and takes less time than picking a lock.
How anti-snap cylinders work
An anti-snap cylinder has a deliberate weak point — a groove or perforation — machined into the outer section of the cylinder. When force is applied to snap the outer part, it breaks at this controlled point.
The key difference: the weak point is positioned so that when the cylinder breaks there, the internal mechanism and cam are not exposed. The door remains locked even after the outer section has been removed.
Higher-spec cylinders add anti-pick pins, anti-drill hardened steel inserts, and anti-bump resistance on top of this. A TS007 3-star cylinder covers all four: snap, pick, drill, and bump.
How to check what you have
Pull up the flap on your letterbox or look at the door edge. If you can see an oval-shaped keyhole on both sides of the door — or one side with a thumb turn on the other — you have a euro cylinder.
Look at the cylinder face around the keyhole. You are looking for:
- A TS007 star rating stamped on the face (1-star, 2-star, or 3-star) - A recognisable brand name: Ultion, Avocet ABS, Mul-T-Lock, Yale Superior, Banham
If the cylinder has no markings, no brand name, or a brand you do not recognise, it was almost certainly fitted as a cheap standard. These are typically not anti-snap.
You can also measure the protrusion. On a correctly installed anti-snap cylinder, the outer section should protrude no more than 3mm from the door face. More than that and even an anti-snap cylinder is at greater risk, because the attacker has more to grip.
What standard to look for
TS007 is the British Standard for high-security door hardware. A 3-star rating means the cylinder alone meets the standard. A 1-star cylinder can still meet TS007 3-star overall if it is used with a 2-star door handle and escutcheon.
Most locksmiths and insurers now recommend TS007 3-star as the minimum for any UPVC or aluminium external door.
BS3621 is a separate standard for mortice locks on timber doors. Do not confuse the two — they cover different door and lock types.
One opinion worth stating
A standard euro cylinder on a UPVC door provides almost no security against a determined attacker. The door itself, the frame, and the multi-point locking mechanism may be strong — but if the cylinder snaps in 20 seconds, none of that matters. We fit anti-snap cylinders on most lock change jobs as a default and tell the customer why. The cost difference is around £30. That is the right call.