The Patio Pacific Cat Door for Horizontal Sliding Windows gives your cats the freedom to come and go as they please without the commitment of more permanent installation in doors or walls. The spring-loaded design expands into the furthest point of your window track for a secure weathertight fit no tools required. This horizontal window pet door features a flexible vinyl flap that cats of all sizes (and even small dogs) can easily pass through.Features:Horizontal window cat door installs quick and easy into your sliding window track (track must be at least 1” thick installation in larger tracks may require some securing).Sliding window pet door insert fits track height between 34" ? 37" 43" ? 46" 46 " ? 49" and 57" ? 60" (for window track measurements within 1" of the lower range (e.g. 35" for the window height range of 34" ? 37") you will need to make sure that you have enough clearance to insert the panel in the track).5 ?" x 8 ¼" flexible vinyl flap accommodates small dogs and cats of all sizes.Sturdy white aluminum frame withstands corrosion due to weather.Durable 3/16” single-pane tempered glass is ideal for mild climates.Benefits:Give your cats the freedom to come and go with this pet door for horizontal sliding windows.Quick quick and easy installation in your window track.Built-in “anti-whoops” feature allows for ¾” adjustment range to account for small errors in measurements.Locking cover snaps on easily restricting access when needed.Installation Instructions:Step 1: Slide the window openStep 2: Place the panel in the trackStep 3: Loosen the thumb screws so that the spring loaded piece moves freely and expands in the trackStep 4: The top of the pet door should fit all the way into the track.Step 5: Remove the cover and start using your door!