Mewoofun Durable Cat Window Perch With Soft Mat For Indoor Cats Holds Up To 25 Lbs And Provides A Stable Hammock For Your CatFeature: Versatile Usage: Our new cat window perch is designed to work with various window types, including those with or without sills, shallow grooves, and even bedside windows. Installation Methods: Depending on the type of window, different installation methods are required. Mounting gaskets are included for windows without sills or those with sills under 3. 54" in width, while drilling is necessary for those with no groove or shallow groove.