Res-Lok Concealed Window Restrictor – Key-Locking Child Safety Lock (LH & RH)
Res-Lok Concealed Window Restrictor – Key-Locking Child Safety Lock (LH & RH Pair)
The Res-Lok is a concealed, key-releasable window opening restrictor designed for open-out side-hung and top-hung casement windows in uPVC, aluminium and timber. It auto-engages every time the window closes and limits the next opening to approximately 100 mm until released with the supplied key — a proven solution for fall prevention in family homes, schools, care environments, social housing and commercial buildings.
Sold here as a matched left-hand and right-hand pair, this is the standard 105 mm arm version of the Res-Lok, the de-facto specification choice on UK fenestration projects where a discreet, robust, auto-locking restrictor is required. The mechanism sits hidden between sash and frame, so when the window is closed there is nothing on show — just a clean, neat finish.
📄 Full Product Guide & Fitting Instructions
Detailed specifications, dimensions and installation guidance — download the complete PDF brochure.
Download Product Guide (PDF) →Key Features
- Approximately 100 mm opening restriction — aligns with widely-referenced UK fall-prevention guidance
- Automatic engagement & automatic locking — no need to re-set after closing the window
- Concealed fitting — invisible when the window is closed, preserving sightlines
- Dedicated key release — controlled access to full opening for cleaning, ventilation or escape
- Stainless steel and zinc alloy construction — self-colour finish, built for long service life
- Retrofit-friendly — suitable for upgrading existing windows as well as new builds
- Conforms to BS EN 14351-1:2006 Clause 4.8 — load-bearing capacity of safety devices, when tested on a specified window system
Compatibility
Suitable for:
- uPVC windows
- Aluminium windows
- Timber windows
- Side-hung and top-hung open-out casement windows
Handing – Left Hand vs Right Hand
The Res-Lok is a handed product — left-hand and right-hand versions are not interchangeable. Handing is determined when viewed from the inside of the building, looking out at the window:
- Left Hand: hinges on the left, handle on the right
- Right Hand: hinges on the right, handle on the left
This listing supplies one left-hand and one right-hand restrictor as a matched pair, so a single order covers two oppositely-handed windows.
Technical Specification
| Feature | Detail |
|---|---|
| Product type | Concealed key-locking window opening restrictor |
| Brand | UPVCSTORE |
| Pack contents | 1 x Left Hand restrictor + 1 x Right Hand restrictor + fixing studs + keys (matched pair) |
| Opening restriction | Approximately 100 mm |
| Operation | Automatic engagement & automatic locking; key release |
| Fitting type | Concealed (sash-to-frame); Eurogroove or surface compatible depending on profile |
| Arm length | 105 mm |
| Screw centres | 37 mm |
| Frame part width | 16 mm |
| Material | Stainless steel & zinc alloy |
| Finish | Self-colour (silver) |
| Window compatibility | uPVC, aluminium, timber – side-hung & top-hung open-out casement only |
| Not suitable for | Tilt-and-turn windows, inward-opening windows, sliding sashes |
| Standards reference | Conforms to BS EN 14351-1:2006 Clause 4.8 (load-bearing capacity of safety devices) when tested on a specified window system; BS 6375 Part 2:1987 also referenced |
| Recommended screws | 4 mm (No.8) countersunk head – not supplied as standard |
Fitting Notes
The Res-Lok is designed for concealed fitting between the sash and frame, with screw centres at 37 mm. Each restrictor comes with the fixing components needed to install on a standard window profile. We recommend professional installation, particularly in care environments, schools and commercial buildings where compliance with project specifications is required.
Full fitting instructions and dimensional drawings are available in the downloadable product guide. If you have any questions about fitting to a particular window system, contact our technical team at sales@upvc-store.com before purchase.
What’s in the Box
- 1 x Res-Lok concealed restrictor — Left Hand
- 1 x Res-Lok concealed restrictor — Right Hand
- 1 x Fixing stud per restrictor
- 1 x Key per restrictor
Note: Screws are not supplied. We recommend 4 mm (No.8) countersunk head screws sized to suit your frame.
Important Specifier Notes
Window restrictors significantly enhance occupant safety but are not a substitute for permanent guarding where guarding is required by UK Building Regulations (Approved Document K) or by project specification. In care homes, healthcare buildings, social housing and other higher-risk settings, project-specific risk assessments and enhanced safety measures may be required.
Always verify compliance requirements with your building control officer, window system manufacturer, or project specifier before installation. UPVCSTORE supplies this product on the basis that the manufacturer’s declared conformance to BS EN 14351-1:2006 Clause 4.8 applies when the restrictor is tested on a specified window system; project-level compliance remains the responsibility of the specifier.
Frequently Asked Questions
Will this fit my uPVC, aluminium or timber windows?
Yes — the Res-Lok is designed for all three frame materials, provided the window is a side-hung or top-hung open-out casement. It is not suitable for tilt-and-turn, sliding sash or inward-opening windows.
How do I know which handing I need?
Stand inside the building and look out at the window. If the hinges are on the left of the frame, you need a Left Hand restrictor. If the hinges are on the right, you need a Right Hand restrictor. This pair listing supplies one of each.
Does it lock automatically every time?
Yes. The mechanism re-engages and locks automatically as soon as the window is closed — no manual re-setting required. The 100 mm restriction is active by default on the next opening, and only releases when the key is turned.
How far does the window open with the restrictor fitted?
Approximately 100 mm. This is the most widely-referenced opening figure in UK fall-prevention guidance for occupied buildings, and is sufficient to provide ventilation while preventing a child from passing through the gap.
Are screws included?
No — we recommend 4 mm (No.8) countersunk head screws sized to suit your frame. This is so installers can match screw length and material to their specific frame type and substrate.
Can I retrofit this to existing windows?
Yes. The Res-Lok is regularly retrofitted to existing uPVC, aluminium and timber casements during maintenance upgrades, void turnarounds and child-safety improvement programmes.
Is this a substitute for permanent window guarding?
No. Where permanent guarding is mandated by Building Regulations or by a specific project specification, the Res-Lok should not be used as a substitute. It is an opening-restriction safety device, not a guard. Always confirm project requirements with your building control officer or specifier.
What if I lose the key?
Spare keys are universal across the Res-Lok range and can be ordered separately — contact our team at sales@upvc-store.com. We recommend keeping spare keys in a secure but accessible location for occupants and emergency use.
Do you offer trade pricing for housing associations and councils?
Yes — for project quantities, framework agreements and rolling supply contracts, please contact our trade team at sales@upvc-store.com for a tailored quotation.
