Endura Flap Thermo Panel 3e for Cats

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  • Most insulating kitty door for sliding glass doors
  • Eliminates heating/cooling loss and drafts
  • Comes in white, brushed aluminum, or bronze (black)
  • Adjustable magnet strength promotes easy training
  • No tools required for installation

The Thermo Panel Cat Doors for Sliding Glass Doors are the most energy-efficient cat doors on the market, resisting -40 degrees Fahrenheit temperatures and winds up to 50 mph. Most patio panel cat doors fall short of insulating effectively due to thin flap door designs, but these doors include adjustable magnets to promote easier training without compromising the flaps sealing capabilities. No matter the season, these sliding glass panels keep your home insulated year-round and provide freedom and independence for your cats. 


  • Heavy-duty, extruded aluminum panel available in three sizes (74 3/4" - 77 3/4", 77 1/4" - 80 1/4" or 93 1/4 " - 96 1/4") to accommodate varying sliding glass door sizes.
  • Custom heights available for track heights outside of the three size ranges.
  • Spring-loaded design does not require any tools for installation.
  • Dual-pane, Low-E glass panel optimizes insulation and minimizes UV and infrared light.
  • Environmentally friendly, polyolefin-polymer flap withstands 50 mph winds and -40 degrees Fahrenheit temperatures.
  • 6" x 11"  flap size and adjustable step-over height accommodate cats of all breeds and sizes.
  • Adjustable magnets encompass three sides of the cat flap for a secure, weather-tight seal. To adjust the magnet strength for easier training, refer to the 'Videos' tab for a short tutorial.
  • Sturdy, ABS plastic security cover included for added safety.
  • Foam weatherstripping and center post weather seal draft stopper included for improved insulation and energy efficiency.
  • C-Clamp Lock included to lock the slider.  Charley Bar can be purchased separately if you prefer.


  • Removable pet door insert is perfect for rentals, vacation homes, or people who want to occasionally take out the panel for full use of the sliding glass door.
  • Avoid making permanent alterations to your home.
  • Flexible flap prevents pinching or snagging when cats use the door.
  • Structurally sound design prevents heating/cooling loss and ensures longevity.
  • Cats can freely exert their independence.
  • Designed, engineered, and manufactured in the USA.

Size Chart

Flap SizeFlap DimensionStep Over RangeOverall Panel Width
Small6" w x 11" h3"-5"11 1/4"


Track Height Adjustment Range is the measurement of your door height from the lowest point of your track to the highest point. Review our Track Measuring Guide. The Thermo Panel 3e Cat Door Panel comes in three adjustable ranges:

  • Short - 74 3/4" - 77 3/4"
  • Regular - 77 1/4" - 80 1/4"
  • Tall - 93 1/4" - 96 1/4" (additional cost)


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:

  • under 74 3/4"
  • 80 1/4" - 93 1/4"
  • over 96 1/4"


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


Additional Information

Flap Material

Engage Polyolefin

Your Maximum Pet Size


Climate Suitability

Severe-4 Season

Sealing Value

Very High, High, Average, Low

Wind Resistance

Very High, High

Installation Instructions

Thermo Panel 3e for Cats Installation


  • Foam weather stripping
  • Center post weather seal draft stopper
  • Panel pet door
  • Sliding door clamp


The aluminum, vertical panel has a patented ‘Adjustable Step-Over’ feature which permits adjustment of the height of the flap to the most comfortable fit for your pet. Generally, the top of the flap should be positioned to be at least 1” (2,5 cm) above the top of the pet’s shoulder (the ‘withers’). If the factory setting is not suitable, please adjust it before proceeding. If the current setting is suitable, proceed to step 4.



Step 1: Lay the entire panel on a flat surface (like the floor). Using a #2 Phillips head screwdriver, remove the bottom side-screws, and loosen the next upper screws one turn. Screws were tightly installed to hold the panel together during shipping; a drill is recommended.

Please Note: If you do not have a Phillips head drill bit skinny enough to fit, let us know and we’ll send you one for free.

Step 2: Once the bottom screws have been removed and the next upper side-screws loosened, the pet door assembly and spacers can be removed by sliding the sections down and out of the panel.

Step 3: Replace the spacers and the pet door assembly by sliding them back in a different order to achieve the desired height. You can move the spacer below or above the flap to raise or lower the flap height.

Please Note: The order of the pieces is important! The piece on the bottom needs to always be at the bottom, as that is where the screws attach.

When finished, replace the bottom side-screws and tighten the next upper-side screws.

Step 4: Loosen the thumb screws at the top of the pet panel. This allows the spring mechanism to move freely up and down.

Step 5: To insert the panel pet door into the top track, push up against the spring mechanism and swing the bottom of the panel up and over the threshold. Seat the panel on top of the small guide rail in the track. If you can’t quite get it in the track, try swinging in from the outside, as the outside track wall may be shorter.

You want to put the pet door in your track before applying any weather-stripping to ensure it fits. If it fits well, move on to the next step. See our tips at the end of these steps if you have trouble.

Step 6: Once you’re sure the panel fits, remove it from the frame and lay it on its side on the ground. Apply the foam weather stripping by peeling back the paper and exposing the adhesive. Unroll it along the edge of the panel, pressing to ensure it adheres. Install on both sides, trim to fit with scissors.

Step 7: The center post weather seal strip (draft stopper) should be installed on the inside of the home. It can install on either the back edge of the sliding door panel or the leading edge of the stationary panel. This strip prevents air leaking between the sliding glass door and the stationary panel. Trim with scissors as needed. Clean the edge of your patio door with rubbing alcohol before installing to ensure a good seal.



Since you cannot lock your sliding glass door to your panel pet door, we have provided you with an alternative locking method to secure your home:


DOORS OVER 80 1⁄4” (203,8 cm) TALL

Installing the threshold mount deadbolt lock: For doors manufactured with the glass slider on the inside track, the lock can usually be installed on the back of the slider using the mounting screws provided. For doors manufactured with the slider on the outside, the lock is installed on the leading edge of the stationary panel.

Step 1: Drill a 3⁄16” (4,8 mm) hole into the frame opposite the steel deadbolt lock. This hole MUST be 3⁄4” (1,9 cm) away from the inside edge of the door’s frame to avoid drilling into the glass. Drilling into the glass will cause the glass to shatter.


DOORS UNDER 80 1⁄4” (203,8 cm) TALL

Installing the sliding door clamp: This clamp has a screw which tightens by hand to prevent the sliding door from moving beyond the clamp’s placement. For doors manufactured with the glass slider on the inside track, the lock can usually be installed on the door’s raised track.

For help with installation, replacement parts or other questions visit or call 805-781-7700 Monday-Friday 7am-4:30pm PT.



Removing Magnets for Training with the Endura Flap

How to Measure a Sliding Glass Door for a Pet Door


Can an intruder remove the Endura Flap cat door for slider from the outside?

No, the thumbscrews are on the inside of the dog door panel, so once installed, the Endura Flap Panel can't be lifted out.

Does the Endura Flap cat sliding door come with locking covers for security?

Yes, there is a slide-in closing cover that you insert on the interior side of the panel. This closing panel will keep your pets inside and keep unwanted critters out.

Do the Endura Flap panels require tools for installation?

Endura Flap sliding glass doors for cats do not require tools, however the lock for the doors in the heights over 80 1/4" would require a Charley bar for maximum security.

Under which height for a Endura Flap sliding cat door would it need to be custom?

74 3/4" is the smallest the off the shelf pet patio door would compress down to.

At which height over 74 3/4" would a the Thermo Panel Cat door insert need to be custom?

Anything from 80 1/4" - 93 1/4", and over 96 1/4" - 100"

What is the absolute minimum and absolute maximum custom heights for Endura Flap Kitty Panels?

The minimum still using the glass would be 35", and the maximum would be 100".

What if I am outside those minimums and maximums for customs?

Then you can contact us in customer service and we can see what we can do to make you a custom door outside our normal ranges. In some cases extra spacers can be used to extend the panel, or they can be used in place of the glass to get under that 35" minimum.

What happens if I got a panel that was a tiny bit too tall?

The top had two 3/4" flanges that you can trim off using a metal cutting blade.

What do I do if I measured, but the panel was too short?

You can slide one of our height extensions to get you an extra 3/4". If you need more than that you can use a piece of wood cut to size and slide that in the top channel.

What does the Draft Stopper do for my sliding panel door?

This will add to the insulation, as it helps to seal up the gap created by the pet door offsetting the slider so it will no longer line up with the stationary frame. These are included in all the Thermo Panel Cat Doors.

Can the Endura Flap Panel come with an electric door?

This door is manual, but we do have some that are available with electronic options. The Dual Scan will control who comes in and out, the Cat Door will do a good job controlling strays coming in, and the Pet Door has a more generous flap size. All of these doors can sense your cat's microchip to known when to open or close. If you do not want a microchip pet door, you can try the High Tech Pet Power Pet Door, which is large enough to accommodate cats and dogs.

Is this door energy efficient?

It is one of the best and the go-to for extreme weather and high wind prone areas. Other related products like the Petsafe Freedom Aluminum Patio Panel and the Ideal Fast Fit patio panel do not offer energy efficiency close to what the Endura Flap offers.

What is the difference between the Endura Flap Thermo Panel and the Endura Flap Quick Panel?

The only difference is the glass. In the Thermo Panel it is dual pane lo-e and the Quick Panel is single pane.

Can this doggie door fit into my sash window?

The Thermo Panel is made to be a sliding glass pet door only, but if you want a pet door for your window, we have a few recommendations. The Petsafe Vertical Window Pet door is an economical solution for sash windows. Additionally, the Ideal Pet Product's "Cat Sash" Cat Door for Sash Windows, which has a tools-free installation for an easy DIY project.


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.

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