Universal Press Syndicate Kool Kongs float, making them a must-have for people with water dogs.

Why are Kongs so remarkable? Part of the answer is durability, and part is flexibility. The basic Kong model stands up to hours of chewing. The rope-equipped Kongs bounce erratically when they land to make "fetch" even more interesting. There's even a Kool Kong for water retrievers. (With three retrievers, I buy Kool Kongs in bulk.)

Probably more important is the use of Kongs to help dogs with time spent alone. A Kong stuffed with peanut butter and pieces of dog treats offers a harmless and healthy alternative to chewing the sofa or scratching the windowsill. There are Web pages devoted to the art of stuffing a Kong: loose filling for introducing the stuffed Kong, and tighter-stuffed and even frozen Kongs for dogs who just love to chew and have time to kill.

While Kongs are mostly sold to dog lovers, their appeal goes beyond the canine realm: A stuffed Kong is good for keeping parrots entertained and out of trouble.

I get news of dozens of new pet products every year and samples of dozens more. Most are just variations on some familiar themes, or are something new that's perhaps nice to have but in no way essential to keeping a pet happy. Few pet products truly stand the test of time. Kong is one of those rare exceptions.

Like many veterinarians, trainers and behaviorists, I find myself recommending Kongs constantly. They're available in almost all pet-supply outlets. Prices vary by model and size.