Kettlebell training has become incredibly popular in the recent years but they were the tool of choice for Russian Lifters over a century ago. They offer all the benefits of dumbbell training plus many more. The thick handles challenge your grip and the position of the kettlebell weight in relation to the handle really works you core.
It can be lifted in various directions like a normal dumbbell or it can be swung around as part of a cardio work out. There are literally hundreds of exercises that can be done using the kettlebell and it can produce a full body work out in a small space.
The weight of a kettlebell hangs a few inches below its handle, which makes it more difficult to control. Everything from your grip to your core has to work harder than if you were using a dumbbell, so you get more out of even standard dumbbell moves. This extra muscle activity means your body burns more calories. Couple that with exercises that target the whole body and you have a formula for significant fat loss.