Sizes vary widely: overall lengths range from about 24.3 inches up to 118.68 inches, heights range from about 18 inches up to 74.01 inches, and widths range from about 24.3 inches up to 37.28 inches.

Common materials include fir and other wood frames, steel or reinforced metal supports, PC board roofing, wire mesh, and some plastic components.

Models vary by design: some are made for sliding windows and list compatibility up to about 37.75 inches wide, while others are designed for double-hung (vertical) windows with widths around 24.3–38.8 inches and generally require a minimum open height of about 16 inches.

Some enclosures include weatherproof roofing (for example, PC board roofs). Others offer removable windproof/insulated covers with a cat door so the space can be draft-blocked in cold months and converted back to an open design in warmer seasons.

Certain designs with three mesh-sided windows provide up to a 270-degree panoramic view and excellent ventilation. Other models include features such as a cat door that allows indoor warm air to flow into the enclosure.

Capacity depends on the model: some smaller window houses are described as accommodating 1–4 cats and supporting up to about 55 pounds, while larger multi-cat enclosures are marketed as spacious for 2–3 cats. Always check each product's stated capacity and weight limit before purchasing.