I've got one robot and four cats. One prefers a regular box (now with crystals). I will be buying another for the summer house we're building. The large size is the only turn off. I'm making sure the closet will accomodate it. The current one in use is in an under stairs, useless, half closet with an electrical outlet in it. Now, it also powers the robot. My friend told me about this a year ago, & I wish I got it sooner.