Custom Endura Flap Cat Door for Horizontal Sliding Windows

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  • Removable panel with built-in cat door fits into a horizontal sliding window track
  • Durable, aluminum frame and pet door made to withstand extreme weather
  • Made with dual-pane, Low-E glass to improve energy efficiency
  • Tool-free installation
  • All custom doors are final sale and non-returnable, please allow 4 - 5 weeks for delivery on all custom orders
  • An email will be sent to you requesting additional information for your custom order

The Endura Flap Cat Door for Horizontal Sliding Windows is made to fit into the existing track of your side-to-side sliding window. It installs tools-free with a spring-loaded design to safely secure into your sliding window track without any permanent alterations (perfect for renters). The removable panel comes with a C-clamp lock, draft stopper and weather stripping. It features dual-pane, Low-E glass that is UV and infrared resistant for maximum insulation value. The flexible flap is lined with adjustable magnets to resist heavy wind and extreme temperatures.

The panels have a 3" spring-loaded height adjustment, so if you have a 48" track, for example, the panel you choose will adjust from 46" - 49" inches.


  • Aluminum frame designed to fit into a window track width of at least 1" thick
  • Comes with a C-clamp lock, draft stopper and weather stripping for security and insulation
  • Dual-pane, Low-E glass allows natural light to enter while blocking out unwanted UV rays and infrared light
  • Flap withstands -40 degrees
  • Fahrenheit temperatures and stays sealed in 50mph winds
  • Magnetic sealing resists heavy winds/storms
  • Flap swings on a rod at the top, avoiding breakage
  • Includes a sturdy locking cover


  • Removable panel benefits all owners, especially renters.
  • Don't need to make any permanent alterations to window
  • Available in white, bronze, or brushed aluminum to match your window frame
  • Pets can enter and exit as they please
  • Locking cover prevents pets from leaving the house when you want to keep them inside
  • Made with durable, long-lasting materials
  • Made in USA

Size Chart

Flap SizeFlap DimensionStep Over RangeOverall Panel WidthRecommended
Pet Height*
Small 6" w x 11" h3" – 5"11 1⁄4"9 – 15"

Your Track Height Adjustment Range is the measurement of your window height from the lowest point of your track to the highest point. The Endura Flap Cat Door for Horizontal Sliding Windows comes in two adjustable ranges:

  • 34"-37"
  • 46"-49"

Review our Track Measuring Guide for more information.

If your measured track height does not fall within one of the ranges above, we can make a custom height! Choose the range that your track height falls into and when ordered you will be asked to give the exact height of your slider track inside very top to very bottom. In each case you will have 3" of height adjustment with the height you specify approximately in the middle of that range. The ranges are:

  • Between 23"-24"
  • Between 37"-46"
  • Over 49"

Custom height option may take up to 4 weeks to special order the glass and build the panel.

CAUTION: If your measured track height is near the bottom of the adjustment range then you should review A Note of Caution.


How easy is this to install?

The spring loaded design makes installation of the cat door panel very easy. No tools are needed, you simply hand loosen the screws pop the door in the track and re-tighten them. Once it is in place you can't remove it from the outside either, so it's safe and secure.

How do I measure to make sure that it fits?

You will need to open the window and measure from the deepest down inside the bottom of the track and all the way up into the track at the top. You will also need to measure how wide the track is, since the panel is 1" thick your track has to have at least that width to be able to accommodate it.

How strong is the seal on the pet door flap?

The magnets are stronger than your typical off the shelf pet door, so they will have to push the flap a bit harder to get it open. You can adjust the magnets in the beginning for training purposes by reducing their strengths, however you will lose some of the sealing power.

Is this just for cats?

Small dogs can also use the flap, as long as they can comfortably make it through a 6"w by 11"h opening.

Does this keep out drafts?

This panel has dual pane insulated glass and the flap seals extremely well so it is great if you are looking for energy efficiency.


How to Adjust the Magnet Strength on an Endura Flap


Endura Flap products have a lifetime warranty against defects in materials and workmanship under standard regular use. Damage caused by not using the product as intended, improper installation, and chewing is not covered under this warranty.

Additional Information

Flap Material


Your Maximum Pet Size

Cats, Large Cats

Climate Suitability

Severe-4 Season

Type of Window

Sideways Sliding

Sealing Value

Very High

Wind Resistance

Very High