Though it bears the same characteristic KONG shape as the Classic, this is a different beast. It is made out of hard, very durable plastic rather than rubber, and unscrews at the base. You pop some of your dog's kibble inside, or a few treats, screw the base back on, and let him at it.
This has been a huge success with Frank. He quickly learned how to knock the Wobbler with his nose or paw, toppling it over so some of its contents spill out through the hole. The weighted base allows the KONG to right itself so the fun can continue.
The idea is that this stimulates the dog's prey drive, making meal times feel more like a natural hunt rather than just food in a bowl. It also slows down a dog's eating speed, reducing the chance of bloat. Above all, though, it's fun.
It can be very noisy depending on your dog's enthusiasm. If used indoors, there is also some chance of damage to furniture or skirting boards (or human ankles) - the plastic is hard, and it can be shoved about at quite a pace, so you may want to use it in a confined space.
Definitely a recommended purchase.