The Omega Paw Door Hanging Scratchy Pad can be hung on any style door knob and is made of durable carpet that is treated with natural catnip oil. The Omega Paw Door Hanging Scratchy Pad is an economical way to provide a scratcher to satisfy a cat's natural instinct to scratch without taking up valuable floor space. The durable industrial carpet lasts a long time before needing to be replaced, and it has a padded backing so it won't mark surfaces.