The Kong has been around for a long time, but over the years they have been re-invented and improved. The Extreme Kong is a lot tougher than the others which is what hard jawed dogs need.
When chosing a Kong always get a bigger size than you think your dog needs. I purchased this one for my older rescue Mongrel (Alsatian x Greyhound x Staffie). She has a big mouth but is not an aggressive chewer and I mainly purchased it as another activity toy for feeding, to slow up her eating!
To use for this purpose (on any size Kong) put something slightly soft and sticky in first (soft cheese / peanut butter etc) then push in some food (I use Iams) then some more soft food and so on, layering it and pushing hard down so it is really compacted. You could even put the stuffed Kong into the freezer for a while to make it harder to get the food out.
Use in this way acts as a boredom buster, something to use their brains to get out the treats and as a way of slowing down eating.
The Kong can be used as a pacifier for a dog that likes to chew. However, nothing is indestructable and must be supervised. Again, always get a size bigger than you think your dog needs, especially for Staffie Types/Bull Breeds/other strong jawed dogs.
The Kong is also a bouncy toy. Because of it's unique shape, when it is bounced hard down to the ground it will shoot off in different directions, thus your dog has to use it's brain and stay alert ot it will miss getting the Kong. I would say that unless you have a large garden, care is needed when using it outside in an enclosed space, or you may well be spending a lot of time disturbing your neighbours to get the Kong back! It is great fun for your dog though and is a variation on the normal ball