The Ideal Lockable Cat Flap Window insert is designed specifically for cats.  The locking cat flap that is used in the insert is rugged and durable. You will never have to replace the flap. It features a 4 Way locking control that allows you to set the door to allow access in the following directions:

4-Way Locking Feature Control:
Open Both Ways
Closed from both directions
Closed going outside - Open coming indoors
Open going outside - Closed coming indoors

This window unit is made of safety glass and has the option of where you would like to pace the cat flap within the unit.  Sometimes having the pet opening on either side or in the center of the insert allows for easier access to the cat.  Both ends of the insert have spring-loaded tension pieces.  These allow for an approx. 5" inch adjustment range that may give you the option of using the unit in more than one window.  No other unit on the market gives you a more generous fitting range.  This item offers a limited lifetime warranty.

Ideal Lockable Cat Flap Window Pet Door
This window unit has 2 adjustment pieces, one on each end giving you the maximum fitting potential between different windows Overall height of unit - 10 3/4" high
Pet Door Used in Unit	Flap Size (wxh)	Flap Type	Ranges of Adjustment (In Inches)	Pricing
Flap is rigid with weather stripping around perimeter. Held in place my magnetic closure. For cats up to 14 lbs. 4-way locking feature	Pet Opening 6 1/4 x 6 1/4"	Solid-Rigid Flap with magnetic closure (Designed for cats)	23-28 27-32 33-38  37-42 45-50	$115.00 (all ranges)
Fabrication usually takes 3-5 business days - then ships via UPS. Units are refundable within 30 days of receipt by customer.
Technical Specifications All Window Sash Units have a spring-load adjuster on EACH end (Info below highlights only one end of unit)