Enormous, but very effective!  Got this for our geriatric big boy named Butters (20 lbs) whose puppy brother was going mining for kitty cookies every day- dog is small enough to get in the little hallway (17 lbs) but can’t turn sideways to dig.  So far so good!  Pretty overpriced- it’s essentially a Rubbermaid bin, but honestly I’d buy it again and again if it keeps the dog out of the box!