30 July 2026

Did you know the stars on your lock tell you how burglar-resistant it is?

SKG*, SKG** or SKG***: what the stars mean, where to find them and when an upgrade makes sense — including the difference anti-snap protection makes.

Take a look at your front-door cylinder: many locks carry a small shield with stars stamped into it. That is the SKG marking, the Dutch product certification for locks and hardware (issued by testing institute SKG-IKOB). One star stands for basic resistance, two stars for heavy and three stars for extra-heavy burglary resistance — tested against the tools and tricks burglars actually use. No shield to be found? Then the lock is usually older or uncertified, and you know at once where your weakest door is.

Why this matters: a burglar takes the path of least resistance, and that path almost always runs through the locks. In one widely used method the cylinder is pulled out of the lock with a puller — anti-snap/core-pull protection (in the cylinder itself or in the security hardware) blocks exactly that. For exterior doors, SKG** with core-pull protection is therefore the common advice; the Police Quality Mark for Safe Living applies the same line to the home's whole shell, and some insurers require it in their terms. Check that last point in your own policy — then you know whether an upgrade pays back twice.

An upgrade is smaller work than it sounds. Usually replacing the cylinder (€ 65-180 each, including fitting) suffices — the lock itself stays in place. If you have several doors done at once, they can be keyed alike: one key for everything, often at a sharper price per cylinder. If the lock or hardware is outdated too, replacing the complete lock (€ 95-250) is the more thorough step; uPVC doors usually already have a multipoint lock, where the cylinder and hardware are the upgrade points.

Useful to know before you reach for tools: swapping a single cylinder is feasible for a handy DIYer (one screw in the faceplate), but the pitfalls are in the details. A cylinder protruding more than a few millimetres is actually more vulnerable to core-pulling, and badly fitted security hardware does not protect. Multipoint locks and hardware are professional work in any case. In doubt, have the fitting included in the job — the guide prices above include fitting, and all ranges are in the price index.

The best moment for this check is a calm one: before the dark months (October-December, when home burglaries peak nationally), when moving house — you never know how many keys are floating around — or simply now, because you happened to think of it. Planned lock work is day-rate work: no surcharge, no rush, and a door that simply keeps the next attempt outside.