Custom Whiskers & Windows Cat Door for Horizontal Sliding Windows

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  • Quick, tool-free installation and removal with spring-loaded frame
  • Height is adjustable up to 3 inches to fit most horizontal sliding windows
  • Durable sash window pet door flap for cats and small dogs
  • All Customs are final sale and cannot be returned, please allow 3 - 4 weeks for custom models to be built and shipped
  • An email will be sent to you requesting additional information for your custom order

The Whiskers and Windows Horizontal Cat flap door for Windows is a fast, hassle-free, affordable way to install a pet door for cats in your home. This aluminum sash window insert requires no drilling or cutting (can be trimmed 3/4" shorter with a metal cutting blade if needed) and can be installed in seconds. Our spring-loaded pet door insert design allows for instant adjustment of up to 3 inches and creates a snug weather-tight fit. This sash window cat door comes in white and black color options, to match your window framing. Great for cats and very small dogs, this dog door will give you and your pets the freedom to come and go as you please. The four-way locking cat flap is included to provide security and access control. Simply use the red and green locking tabs to close it so nothing can enter or exit, allow access in and out, allow the pet to come in only at a certain time, or out only so they can't come back in until you allow it. 


  • Great for renters with no-tool installation
  • Adjustment ranges fit most windows and custom options can be made, however, they are non-returnable
  • Small can fit cats up to 10Lbs and the Large is good for cats and small dogs up to 15Lbs
  • Easy to install
  • Lightweight flap is easy to use
  • Flap is lockable
  • Allow 3-4 weeks for any custom options

Size Chart

Flap SizeFlap DimensionOverall Panel Width
Cat Flap 6"w x 6"h13"
Large Cat Flap7 1/2"w x 8"h15"


Window Width Adjustment Ranges

  • 34" - 37"
  • 46" - 49"
  • Custom Non-Returnable 23" - 34"
  • Custom Non-Returnable 37" - 46" 
  • Custom Non-Returnable Over 49"


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


1 Year Limited Warranty

The manufacturer guarantees your purchase for a period of one year from the date of original purchase against any defect arising due to faulty materials or manufacture. Accordingly, any defective item will be repaired free of charge or replaced at the manufacturer’s option provided that the defect has not been caused by neglect, misuse, or normal wear and tear and proof of purchase date is supplied. Your statutory rights are not affected.

Additional Information

Frame Material


Flap Material


Flap Colors


Dual or Single Pane

Single Pane 3/16" Thick

Your Maximum Pet Size

Cats, Large Cats, Small Dogs

Climate Suitability

Temperate-3 Season

Type of Window

Sideways Sliding

Flap Design


Ability to Lock Flap

Deluxe (4-way lock)

Can Be Installed In

Sideways Sliding Windows

Sealing Value


Wind Resistance


Insulation Value


Installation Instructions

Measure Your Pet

Step 1: Height and Width of your pet: This pet door opening is 6" wide x 6" tall for the small size. The large measures 7 1/2" wide x 8" tall. Be sure to include the 3-inch stepover when calculating opening height.

Step 2: Height of window track: Measure inside your track from the deepest point on the bottom to the deepest point on the top. Choose the size that will fit between 34"-37" or 46"-49". If your window track measurement is within 1" of the bottom (35" or 47") then you will need to make sure that you have enough clearance to get it into the track. If your window measurement is outside of either of these ranges it will not fit properly.

Step 3: Width of window opening: Your window must be able to open 13" wide for the small size and 15 1/2" wide for the large size.

Step 4: Track thickness: must be at least 1" thick. It will fit in wider tracks but may need to be secured.



Step 1: Release the automatic height adjustment by turning the knobs located near the top of panel counter-clockwise and pressing. The height adjustment panel should fully extend upward (pull up on panel if necessary).

Step 2: Open the sliding window.

Step 3: Insert the cat door with the knobs facing inside. Place the top edge into the top track of the window. Lift up and swing the lower portion of the panel into the bottom track.

Step 4: Slide the Whiskers door against the door jamb. Make sure that top is fully extended (not tilted to one side) and the bottom of the panel is on the ridge in the bottom track.

Step 5: Hand-tighten the knobs by turning clockwise to lock the pet door in place.



How big of a dog can go through this?

The large cat door flap would accommodate a dog about 15Lbs, and no more than 10" at the shoulder.

Can you lock it?

Yes, this cat door window insert has a 4-way lock which means you have 4 different access options. You can set it for totally locked, so nothing can go in or out. Open, so they can go in and out as they please. In only, so that once they come in they can't go back out until you let them. Or out only, so once the exit they will need you to let them back in.

Is the doggy flap see through?

There is a slight tint, but you can see through it.

Is it hard for really small pets to use?

The flap is very easy to push open so small pets have no trouble using it. It is rigid though, so if your pet is timid we would recommend the Petsafe Horizontal Cat door for Windows.

Could this be used leading out to a catio?

Yes! In fact that is one of the more popular reasons customers get these doors.

How can I control which pet can use the door?

You will need to get an electronic pet door. The Sureflap microchip cat flap can detect the unique serial number on your cat’s microchip to lock and unlock the door. While not a microchip pet door, the Cat mate is just as effective as it uses collar tags as a “key” for your cats.