Start with one shape and encourage your pup to interact with the toy. Once he easily empties the toy, add another Link to increase the challenge. Linkables "grow" with your dog's skills. When your dog has mastered two Links, add a third, then a fourth to keep the fun going!
This product says on it "not for destructive chewers". What they mean is if your dog chews at all they will destroy it in a matter of minutes.
durable treat toy by rogue retriever09/07/2010
My lab loves the linking treat toys. He gets some of his breakfast kibble and an assortment of treats and chewable supplements divided among 2 or 3 links, including the elbow and ball, keeping him occupied for a good half-hour. The toys are very resistant to his strong jaw despite showing many teeth marks. The elbow is stronger and more durable than the straight link, whose spiral design creates weak spots that my dog has bitten through. The ball is great for kibble and big enough that my dog can't chew through it. He can take apart the links fairly readily, but it's not an issue, thanks to the recessed small flaps, which are shaped like clogs at one end (with the bigger opening) and prongs at the other, where a smaller opening resists fall-out better. The recess is deep enough so my dog can't chew these vulnerable flaps, a big improvement over many rubber treat toys. Although not soft, the rubber lands on my hardwood floors with no damage and a thud I can live with, unlike a hard plastic cube or bubble. I give this highest marks for a treat toy. The one drawback: it's har to find treats that fit the openings but don't come out too quickly now that my dog has mastered his flinging technique.