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Sash Limit Safety Lock for Sliding Windows, Spring Loaded, Double Drilled
- SKU:
- SL-5901DD
- Availability:
- Usually ships within 24 hours.
Sash Limit Safety Lock for Sliding Windows, Spring Loaded, Double Drilled
SKU: SL-5901DD
Window opening hardware · SKU SL-5901DD
Help Limit the Opening of Compatible Sliding & Hung Windows
This compact spring-loaded sash limiter is intended to create a physical stop in the travel path of a compatible horizontal sliding or vertical hung window sash. Its double-drilled body provides top- and side-mounting hole options, giving an installer flexibility to suit different window profiles.
This style is also commonly searched for as a window safety lock, sash stop or window opening restrictor. The final permitted opening is determined by the window design, mounting location, fasteners, installation and condition of the window. Compatibility and the resulting clear opening must be checked at every installation.
Important: an ordinary insect screen is not fall protection
Screens are generally intended to keep insects out. Do not rely on an ordinary screen to prevent a person or child from falling. Window safety should also consider supervision, furniture placement, guards, glazing, egress requirements and regular inspection of the complete window system.
How this sash limiter works
A plain-language overview of the product’s intended function.
1. Installed in the sash path
The body is secured to a suitable part of the frame or sash where the moving sash can contact the projecting stop.
2. Creates a physical stop
When engaged, the stop is intended to interrupt sash travel at the mounting position selected for that window.
3. Opening must be verified
The clear opening must be physically measured after installation. The part does not create a preset opening by itself.
Traditional applications
Conceptual examples only. Actual placement depends on the construction and geometry of the specific window.
Conceptual illustration — not an installation drawing.
Horizontal sliding windows
The sash moves left or right. A compatible limiter may be positioned so the moving sash contacts the stop before reaching its full travel. Confirm that the interlock, weather seals, glass and concealed components are clear of the proposed mounting area.
Conceptual illustration — not an installation drawing.
Vertical hung windows
The sash moves up or down. A compatible limiter may be installed where the moving sash can contact it at the selected opening. Check for balances, jamb liners, tilt hardware, weather seals and other concealed components before drilling.
What this component can — and cannot — do
Understanding the product’s scope is essential to choosing and using it responsibly.
Intended function
- Help restrict sash travel on a compatible sliding or hung window.
- Provide top- or side-mounting hole options through its double-drilled body.
- Serve as one mechanical component within a broader window-opening safety plan.
- Support repeatable opening control when correctly positioned, fastened, tested and maintained.
Do not assume it will
- Make a window childproof, fall-proof, tamper-proof or impossible to bypass.
- Replace supervision, a required guard, a certified protective screen or another required system.
- Reinforce or change the glass, glazing, frame, screen or structural capacity of the window.
- Act as a primary forced-entry security lock unless that use is separately documented.
- Establish building-code, fire-code, property-standard or by-law compliance by itself.
Before ordering or installing
Similar-looking windows may have very different frame profiles and concealed components.
- Confirm that the sash moves horizontally or vertically and will physically contact the limiter.
- Identify a solid, suitable mounting surface with adequate substrate for the selected fasteners.
- Check that drilling will not contact the glass edge, insulated glass unit, glazing bead or seal.
- Check for balances, interlocks, tilt hardware, weather seals and other concealed components.
- Confirm that the device will not interfere with required emergency escape, ventilation or accessibility.
- Determine the intended opening and verify it by measurement after installation.
- Inspect the window, sash and frame for damage, looseness, distortion or deterioration.
- For multi-unit work, confirm the application across each window type rather than assuming all units match.
Fasteners and drilling location are application-specific
A universal screw size or drilling location is not provided because window materials, wall thicknesses and concealed components vary. Use fasteners suited to the actual frame material and available substrate. Where the mounting condition is uncertain, have the window assessed and the hardware installed by a qualified person.
Installation, verification & maintenance
This is a general verification sequence, not a substitute for manufacturer instructions or an on-site assessment.
- Inspect the complete window. Confirm its operating type, condition and any emergency-egress role.
- Confirm compatibility. Make sure the stop can be securely mounted and contacted by the moving sash.
- Choose the intended mounting position. Account for the window geometry and desired controlled opening.
- Verify the drilling zone. Keep clear of glass, seals, balances, interlocks and concealed hardware.
- Use appropriate fasteners. Fasteners must suit the frame material, thickness and available substrate.
- Operate and measure. Cycle the sash repeatedly and measure the net clear opening at the widest passable point.
- Check security of attachment. Confirm that normal operation does not rotate, loosen or dislodge the device.
- Inspect regularly. Recheck after tenant turnover, repairs, reported tampering, damage or any change in operation.
About the 100 mm (approximately 4 in) reference
A 100 mm opening limit appears in certain Ontario building requirements, municipal provisions and safety guidance. It is not a universal rule for every window, and this product does not automatically create or certify a 100 mm opening. The applicable requirement can depend on the building, occupancy, sill height, exterior drop, window location, municipal rules and whether the window is required for emergency escape.
As one example, the City of Toronto’s consolidated Chapter 629 document available online (dated April 30, 2025) describes multiple protection options for certain apartment windows. Its controlled-sash option pairs an opening restricted to not more than 100 mm with a heavy-duty screen conforming to CAN/CSA A440. A sash limiter alone should therefore not be assumed to satisfy that provision.
Confirm the current requirements for the specific property with the local Authority Having Jurisdiction and, where appropriate, a qualified building, fire-safety, engineering or installation professional.
Sash opening, screens and glass are different safety questions
Sash-opening control
A sash limiter addresses how far the operable part of a compatible window can travel when the stop is engaged.
Screens or guards
Ordinary insect screens are not fall barriers. A guard or tested protective screen is a separate component with separate requirements.
Glass and glazing
This hardware does not alter the glass. Safety glazing, impact performance, retention and framing must be assessed separately.
Managing multiple units or an entire building?
Ontario Glazing Supplies can assist with hardware identification, product availability and bulk-quantity needs. For a useful initial review, send clear information for each window type rather than only a close-up of the part.
- A full photograph of the window from the interior.
- Close photographs of the intended mounting area.
- Whether the sash moves horizontally or vertically.
- Relevant frame, sash and opening measurements.
- Required quantity, building municipality and number of window types.
- Photos of any existing limiter, guard or screen system.
Frequently asked questions
Direct answers to common window limiter and safety-lock questions.
Does this sash limiter make a window childproof?
No. It is a mechanical sash-limiting component. It should not be described or relied on as childproof, fall-proof or as a substitute for supervision and other appropriate safeguards.
Will it automatically limit my window to 4 inches or 100 mm?
No. The opening depends on the mounting position, window geometry, installation and condition of the window. The net clear opening must be measured after installation.
Is “double drilled” the same as double locking?
No. “Double drilled” refers to mounting-hole options on the top and side of the body. It does not mean the product has two independent locks.
Can I use it as the main security lock on my window?
Do not assume so. This listing describes a sash travel limiter, not a primary forced-entry security lock. Use the window’s appropriate locking hardware for security unless another use is supported by manufacturer documentation.
Can it be installed on a bedroom or emergency-egress window?
Do not assume that it can. Restricting a required emergency-escape opening can create a separate life-safety hazard. Suitability must be confirmed for the specific window and accepted by the applicable Authority Having Jurisdiction where required.
Does this product make the glass safer or stronger?
No. The limiter does not alter, reinforce or upgrade the glass, glazing seals, frame or retention system. Glass type and human-impact requirements are separate considerations.
Does an ordinary window screen prevent falls?
No. Ordinary insect screens are generally designed to keep insects out and should not be relied on to prevent a person or child from falling.
Is this product certified to ASTM F2090 or automatically code compliant?
No such certification is claimed on this listing. This product should not be represented as an ASTM F2090 Window Opening Control Device or as a complete code-compliance solution unless separate manufacturer test and certification documents establish that status for the exact product and application.
Learn more about window opening safety
Read our plain-language guide for property managers, owners, installers and families: Window Opening Safety in Ontario: Limiters, Guards, Screens, Glass & the 100 mm Reference.
Important safety and compliance notice: This product is a sash-limiting hardware component intended to help restrict the travel of compatible sliding or hung window sashes when correctly selected, positioned, installed, tested and maintained. Its performance depends on the window design and condition, mounting location, substrate, fasteners, installation, use, inspection and maintenance.
Ontario Glazing Supplies does not represent that this product is childproof, fall-proof, tamper-proof, a window guard, a certified protective screen, an ASTM F2090-compliant Window Opening Control Device, or a complete fall-protection or regulatory-compliance system. It does not alter the glass, screen, frame or structural performance of the window. It must not interfere with a required emergency-egress opening unless suitability has been confirmed for the specific application by the applicable Authority Having Jurisdiction and qualified professionals.
The purchaser, property owner and installer are responsible for confirming compatibility, suitable fasteners, installation location, resulting clear opening, egress requirements and all applicable current requirements. This page provides general product and safety information only and is not legal, engineering, architectural, fire-safety or building-code advice.
