Our medium-sized Australian Shepherd really loves this Archstone Pets Porcupine Snuffle Mat. The yellow loops and the stiff felt discs are easy for humans to fit/hide treats inside or under (so far we have used broken up Beggin' Strips Bacon treats, freeze-dried PureBites chicken treats, or some of her Acana brand kibble), but the discs and loops still pose enough of a challenge for our dog that it keeps her entertained. I would rate this as an Easy/Simple puzzle level. The whole mat itself is lightweight, so a smart puppy may figure out that they could grab a corner and shake/lift up the whole thing potentially, but it does have a stiff/grippy backing to the mat that helps keep it from sliding too much on carpeting (although may slide on wood/tile flooring).