Thin Cat Door for Windows, Pet Doors and Sliding Door, Safety Pet Door with 4 Way Lock, Weatherproof Cat Flap for Thin Door and Wall(Medium, Outer Size 7.76 * 7.5 * 0.78in) Review
By Marcus Bell · Dog nutrition editor · Published 2026-05-07 · Updated 2026-07-06
The Lessmon thin cat door is built for windows, screens, and sliding doors as thin as 0.1 inches, and its 4.4 star rating across 2,300 reviews shows it's a trusted pick for tight installs.
Owners who need a cat door for a thin surface like a window, screen, or sliding door where a standard thick frame door won't fit.
Skip if
You need a door for a standard interior or exterior door, since this is built specifically for thin surfaces between 0.1 and 0.78 inches.
Breed size Extra Small, Medium, Small
Priced 69% below the category median ($31.95 across 49 tracked models)
Our scorecard
4.4/5overall
Owner rating4.4/5
4.4 average across 2,300 owner ratings
Popularity3.9/5
2,300 owner reviews, more than most models here
The overall score is owner satisfaction weighted by how many reviews back it, so a high rating from few reviews counts for less. The bars below show where this model stands against the other dog and cat food, health, gear and grooming we track in this category on price, popularity and size. Context, not marks against it, and our read of the data, not a lab test.
Overview
["This Lessmon cat door is purpose built for thin installations, fitting surfaces from just 0.1 inches up to 0.78 inches thick, which covers windows, screens, and sliding doors that standard cat doors can't accommodate. The medium size measures about 7.76 by 7.5 by 0.78 inches overall, with a magnetic flap closure and a 4-way lock.", "It's rated for cats as well as small and medium dogs, and Lessmon describes it as weatherproof, making it suitable for thin exterior surfaces like sliding glass doors or window openings. At $9.99, it's the most affordable door in this lineup.", 'With 2,300 reviews and a 4.4 star average, this is the second most reviewed door in this set, showing strong sustained demand for a thin profile pet door solution.']
Pros
Fits very thin surfaces down to 0.1 inches, ideal for windows and sliders
Strong 4.4 star average across 2,300 reviews
4-way lock and magnetic flap combination
Lowest price point in this category at $9.99
Cons
Maximum thickness capped at 0.78 inches, not for standard doors
Plastic frame construction may wear with heavy daily use
0 units recorded as bought in the past month at time of review
Specifications
Breed size
Extra Small, Medium, Small
Performance notes
Designed for thin surface installs between 0.1 and 0.78 inches thick, this door uses a magnetic flap with a 4-way lock, plastic frame, and ABS flap material, rated for cats plus small and medium dogs.
What buyers say
A 4.4 star average from 2,300 reviews signals broad, consistent satisfaction, making this one of the more proven thin profile cat doors despite no recent purchases recorded in the past month.
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