• Custom-fit Endura Flap Cat Door for horizontal sliding windows
  • Durable aluminum or vinyl frame with 3/16" clear safety glass, which is 59% thicker than the standard for enhanced durability and increased energy efficiency
  • Easy installation, perfect for renters with no permanent alterations needed
  • Comes with C-clamp lock, draft stopper, and weather stripping for security and insulation
  • Flap remains flexible in -40°F temperatures and stays sealed in 50mph winds

Endura Flap Custom Cat Door for Horizontal Sliding Windows

Custom Height Extreme Weather Sliding Window Access

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Regular price $831.00

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Color: White
Height Adjustment Range
Frame Material


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Custom-built to your exact window dimensions, this tool-free sliding insert pairs insulating safety glass with double-walled magnetic flap technology to give your cat year-round access that resists severe weather and wind.

The Endura Flap Custom Cat Door for Horizontal Sliding Windows offers an energy-efficient, custom-fit pet opening designed specifically for horizontal sliding window tracks. Engineered with heavy-duty frame construction and high-performance flap technology, it provides your cat independent freedom without requiring permanent window modifications.

Custom Fit for Sliding Windows
Custom built to your exact window dimensions, this insert slides directly into your existing window track for a secure, draft-free seal. The spring-loaded design allows up to 3-1/2" of built-in height adjustment, making installation and seasonal removal quick and tool-free.

Heavy-Duty Frame & Safety Glass
Available in durable aluminum or vinyl frames to match your home's aesthetic. Aluminum models fit tracks at least 1" wide, while vinyl models require tracks at least 1-1/2" wide. The insert features single-pane safety glass for maximum natural light and energy insulation.

Award-Winning Weather Protection
The patented Endura Flap utilizes magnetic seals and dual-pane construction to stay sealed in wind gusts up to 50 mph and remain flexible in temperatures down to -40°F, ensuring optimal year-round thermal protection.

Enhanced Security & Locking
Every panel includes an Endura Flap Slide Lock to secure your sliding window track, alongside a sturdy top-loading Endura Flap Locking Cover to control pet access when needed.

Installation & Fit

  • Custom built to your window's exact height dimensions with up to 3-1/2" of spring-loaded height adjustment for a draft-free seal.
  • Requires horizontal sliding window tracks measuring at least 1" wide for aluminum frames or 1-1/2" wide for vinyl frames.
  • Constructed with heavy-duty extruded aluminum or vinyl framing and single-pane safety glass.
  • Includes the Endura Flap Slide Lock to secure the sliding window track, a top-loading Endura Flap Locking Cover, draft stopper, and weatherstripping.
  • Tool-free DIY setup installs directly into existing window tracks in under 5 minutes with zero drilling or permanent modifications.

Best Suited For

Ideal for:

  • Extreme weather and high-wind locations, featuring heavy magnetic seals rated for 50 mph winds and sub-zero freezing weather.
  • Non-standard horizontal sliding window heights requiring a tailored, made-to-measure fit with built-in spring adjustment.
  • Renters and homeowners seeking a fast, tool-free installation that slides into place with zero drilling or permanent modifications.
  • Cats and small pets comfortable with a heavy-duty, double-walled insulated flap.
  • Window tracks measuring at least 1" wide for aluminum or 1-1/2" wide for vinyl frames.

Not ideal for:

Questions

How long do Endura Flaps typically last?

The lifespan depends on usage and weather exposure, but Endura Flaps are designed to last significantly longer than standard vinyl flaps. Many homeowners only need to replace them after years of heavy use.

Can you lock the pet door?

It comes with a latched closing cover, and you slide that in on the inside of the house.

Does this insulate well in severe weather?

This door has superior insulating capabilities. The double flaps have magnets that seal all the way around, and will stay closed in wind gusts up to 50mph. The Low-e glass also compliments the insulating value of you new vinyl door. It is our #1 recommendation for extreme climates.

Explore all questions
Product Details

Product Details

The Endura Flap Custom Cat Door for Horizontal Sliding Windows offers an energy-efficient, custom-fit pet opening designed specifically for horizontal sliding window tracks. Engineered with heavy-duty frame construction and high-performance flap technology, it provides your cat independent freedom without requiring permanent window modifications.

Custom Fit for Sliding Windows
Custom built to your exact window dimensions, this insert slides directly into your existing window track for a secure, draft-free seal. The spring-loaded design allows up to 3-1/2" of built-in height adjustment, making installation and seasonal removal quick and tool-free.

Heavy-Duty Frame & Safety Glass
Available in durable aluminum or vinyl frames to match your home's aesthetic. Aluminum models fit tracks at least 1" wide, while vinyl models require tracks at least 1-1/2" wide. The insert features single-pane safety glass for maximum natural light and energy insulation.

Award-Winning Weather Protection
The patented Endura Flap utilizes magnetic seals and dual-pane construction to stay sealed in wind gusts up to 50 mph and remain flexible in temperatures down to -40°F, ensuring optimal year-round thermal protection.

Enhanced Security & Locking
Every panel includes an Endura Flap Slide Lock to secure your sliding window track, alongside a sturdy top-loading Endura Flap Locking Cover to control pet access when needed.

Size icon Sizing & Fit

Size Chart

Flap Dimensions:

6"w x 11"h

The entry way your dog goes through.

Overall Panel Width

11 1/4"

How wide your panel is.

Flap dimensions
Panel width
Step over height

Step-Over Height

3"

The distance from the bottom of the panel to the bottom of your flap.

Flap Size Flap Dimension Step Over Range Outside Frame Dimension Recommended Pet Height
Small 6"w x 11"h 3" 11 1/4" 9" - 15"

Do not know which size to get? Here is a measurement guide to help you out.

Aluminum panel has 1" framing, measure your track width to make sure that your window will accommodate the panel.

If your measured track height does not fall within one of the ranges above, we can make a custom height. Custom height option may take up to 4 weeks to special order the glass and build the panel. If your measured track height is near the bottom of the adjustment range then you should review A Note of Caution.

FAQs

FAQ

Reviews

Customer Reviews

Request Freight Quote

Track heights exceeding 106 inches (107" or higher) may require additional shipping charges. Please provide your contact information for a custom freight quote, and our team will follow up during normal business hours.