User-powered weight fires like piston, using kinetic energy to cause quick bursts of muscle contraction for short, high-intensity workouts.

A modified dumbbell that oscillates, purportedly increasing the effects of exercise. 

Get lean and sculpted arms & shoulders
Work-out your arms, shoulders and chest in just 6 minutes a day
Much more effective then dumbbells, this is the revolutionary way to shape and tone your arms!

MAKES A GREAT GIFT TOO !    ;)