A Kettlebell (KB) looks a lot like a canonball with a handle attached to it and can be used for traditional lifting and strength conditioning although it´s real value is found in different kinds of ballistic exercises that involve major parts of the body to either perform the exercise or act as stabilisors of the core and shoulders.

In my own opinion it represents one of the most useful and volatile pieces of training equipment known to men. With just one or two KB of the right size we can create a full body workout by lifting, swinging and pressing as well as using them as supporthandles for body weight excercises.
We can work our strength, endurance, cardio, aguility, flexibility, mobility, stability and balance - often even using the same exercise - and (in a shorter period of time then You would imagine) build the kind of functional strength that is extremely useful in everyday life.

On top of all other it´s rather time saving. A session is typically 20-30 minutes - and that should be enough for anyone to feel thoroughly worked through and enjoyably tired.