Product details:

The incredible space-saving design simply attaches to any door. No more valuable floor space is taken up by bulky cat trees and cat furniture. With top and bottom straps to securely lock the condo in place, it provides rigid security for your cat's most ambitious playtime. A mesh window on the middle level allows cats to lookout. This 3 story Hangin' Cat Condo also was designed with a comfortable lounging or sleeping surface on the top.