Perfect Pet by Ideal Chubby-Kat Cat Sash Window Cat DoorUnlike other parts of the world, 90% of companion cats in the United States never go outside. Yet millions of owners have discovered that a cat flap is the ideal way to move the litter pan from the living area of the home to the garage, basement or utility room. And with the litter pan goes the dust, tracking mess, and odor. Also those with dogs and cats can segregate the cat's food and waste from a hungry or curious dog. Our Perfect Pet by Ideal Chubby-Kat Cat Sash Window Cat Door has an unbreakable Lexan(TM) flap and features a 4 way lock. This means that you can set the lock to give free access in or out; in but not out; out but not back in; or completely locked in both directions. This cat door is specially designed for sash windows. Made with high quality thermoplastic and aluminum construction with a white finish. Installs easily!