Pet doors installed into windows can be one of the easiest ways to allow your pet access outside. Window inserts are available for Sash Windows (Open up & down) as well as Side Sliding Windows (Side sliding). Moore Pet has the largest variety of window pet door options for both cats an dogs from electronic doors for cats and small dogs to flexible flap models for the extra large dogs. These window pet doors are designed to rest in the track that your window glides. Weatherstripping is included to seal gaps. Additional weatherstripping is easily found at local hardware stores as well. If you would like any assistance please call us at 1-800-829-7876 and speak with our pet door experts.