Shake Weight, the continuous shaking motion works the arm muscles (biceps and triceps) as well as the chest and shoulders at such a level that muscle development occurs when using the equipment at least six minutes each day over a very short period of time.
The technology behind the Shake Weight may sound a little complicated. However, if fast & simple is what you're looking for in exercise equipment, it doesn't get much better than the Shake Weight. The equipment consists of a large dumbbell component that weighs about three pounds. The product does requires no batteries or any assembly. You can instantly start toning your arms.