Buy gap restrictors for safe gap ventilation

A door restrictor is an ingenious piece of door or window hardware that allows you to leave the door or window slightly ajar. For fresh air. Without being able to open it fully. The mechanism blocks the door at an opening of 5-15 cm, allowing you to ventilate at night or while you are away without the risk of burglary. On this page, you can read how it works, what types are available, and which SKG level you need for insurance requirements.

Window stay

AXA, DX and HAFELE door stay — overview hub gap lock for inward-opening front and back doors in matte black and chrome-plated stainless steel for residential and office use.

Door Stop

How does a door chain actually work?

A door restrictor consists of two parts: an arm mechanism mounted on the door frame or door, and a strike plate or pin on the opposite surface. When the door is closed, the arm folds flat. If you want to leave the door slightly ajar, you lift the arm and hook it into the strike plate. The door can now open to a set distance (typically 5-15 cm) but no further. A burglar cannot stick their hand through the opening to reach the cylinder or pull the door open.

To close, unhook the arm and push the door shut. The system works mechanically; no electronics, no battery. Suitable for years of maintenance-free use. For the bedroom door where you want to ventilate at night, or for the front door where you want to receive a package delivery person through the gap without letting them fully inside, it is an indispensable addition to the standard lock.

What is the difference between inward and outward opening?

Inward-opening (Intersteel Curve Inward-opening, AXA IN, HAFELE Inward-opening) is for doors that open inwards. The standard in Dutch homes for front doors and most interior doors. The door restrictor is mounted on the inside of the door and the frame, with the arm on the hinge side. Outward-opening (Intersteel Curve Outward-opening) is for doors that open outwards. Less common for residential front doors, but typical for back doors leading to the garden or for commercial properties.

The mounting side therefore depends on the opening direction of your door. For those unfamiliar with their door: stand in front of the door with the hinges in view. If the hinges are on your side and the door opens towards you when you operate the lock, it is inward-opening. If the hinges are on the other side and the door opens away from you, it is outward-opening. If in doubt, measure the existing lock and send a photo.

Which SKG level do you need for insurance?

SKG V1® is the lowest SKG certification for window restrictors and means that the mechanism withstands a burglary attempt for at least 15 seconds. This is sufficient to deter an opportunistic burglar. For the Police Quality Mark for Safe Living (PKVW), SKG V1® is the minimum recommended. The Dulimex DX Window Restrictor and Exceptor® are both SKG V1® certified in our collection.

For higher security requirements, opt for SKG V2® or V3®, which offer resistance for 30 and 60 seconds respectively. These levels are particularly relevant for commercial premises and homes with a high risk of burglary. For most residential houses, V1® is sufficient. The complete burglary system (door hardware + cylinder + lock) determines the final waiting time for a burglar, not just the door restrictor itself. For the complete package, see security hardware and cylinders.

Which models and brands do we carry?

Intersteel Curve is our most popular series. Modern round arms in brushed stainless steel and matte black, available in inward and outward opening versions. The design complements modern interiors thanks to its streamlining and sleek finish. AXA offers classic versions (AXA Kierstandhouder IN matte black and the Oyster Combi window lock) specifically designed for window applications. For SKG-certified models, select DX (Dulimex). The Exceptor® Kierstandhouder Binnenaand SKG V1® is one of our top sellers. HAFELE has a matte black inward opening version for German design enthusiasts.

For specific window applications, there is a separate category: stainless steel window stay contains 8 products made specifically for window operation. For other ventilation solutions, see also window stays , which have a similar function for window ventilation but use a mechanism that locks the window position.

How does this fit into your broader security package?

A door restrictor is an additional component, not a replacement for a good door or window lock. For optimal security, combine it with SKG-certified backplate front door hardware and a good cylinder . For burglar-resistant front doors, a multi-point lock is also recommended, which locks in multiple positions simultaneously. For window security, there are more specific combinations. See lockable window handles as an addition to the door restrictor.

For those who want to review all burglary protection options, our main security hardware category a complete overview. Our advisors are happy to help you choose the right level (PKVW-A, B, or C) depending on your living situation and any requirements from your insurer.