Give your cat the best possible view with Prevue Pet Products TabbyNapperBounce and Spring. TabbyNapperBounce and Spring is the first portable window bed for cats that works on both casement and double hung windows. The cat bed cradles cats in fleecy comfort, the Velcro strap underneath the cover adds extra support. Cats will be engaged and entertained for hours, preventing boredom and destructive behavior. Perfect for homes with multiple cats,the sturdy steel frame construction can hold several cats at once up to 35 lbs. Tabby Napper is recommended for both kittens and adult cats. The cover is removable and machine washable. Prevue Pet Products TabbyNapperBounce and Spring measures 24inches Long and 14 .75 inches Wide.The Tabby Napper is easy to assemble and install, no tools needed. The TabbyNapperBounce and Spring fits in double hung aka vertical sliding windows and casement windows aka crank windows . TabbyNapperBounce and Spring is compatible with casement and double hung windows only. For the stability and protection of your pet and home, keep the window closed once your Tabby Napper is installed. Consider the purchase of a TabbyNapper Replacement Cover to use while your primary cover is being washed/dried. Requirements for installation: Windowsills must be a minimum of 3inches deep and 24 .5 inches Long TabbyNapper is not recommended for windows with plantation shutters To install TabbyNapperBounce and Spring permanently, owners can tightly screw brackets into the windowsill using two screws. Required tools and hardware not included