I purchased a small buster cube for one of my cats, who is an expert at quickly deciphering puzzle treat dispensers. The ones that merely require tipping or rolling a ball are too easy, and the Nina Ottoson puzzles are conquered in less than ten minutes. However, more than six months later, this cat probably spends an hour each day occupied by the Buster Cube, deftly rolling it over the rounded corners to shake out his breakfast.No other puzzle toy I've met can keep clever animals occupied for as long as the Buster Cube. My cat is definitely less anxious and restless since getting it. I just wish that they made a version that was easier to clean, and perhaps even chew-proof (I wouldn't leave the hard plastic unattended with a hard-chewing rottweiler, for example). Now that we're getting a new puppy, the Buster Cube is the first toy on my list.