power ball workout

ok if you have never seen this ill show a ball that when you spin can genarate a force of about forty with the small balls) with the big one the siver ball much more force, it can make your hands strong, and aslo imrove your grip, you just have to do it to see what its sure a hand full know what it is, and some will be new to you have to get it the way it makes you feel is a challange no matter what, you can act like your a item while you spin it, mimic a workout that will fit in your pocket br, br,