Ok so i order the shake weight from the Amazon store and i just receive it , im not gonna go through the hassle of s & h. when I open the box , i be as exit as a little kid in a candy store , i mean who would not be ? so i start use it , think that that be how you turn it on -lrb- do not read the manual -rrb- but no luck , so i put in the dvd and it do not say anything about turn it on , so i get angry and start read the manual and it say and quote : `` unlike the impression create by the rapid motion of the device , the Shake Weight be NOT battery power , the user generate the movement . '' I use the shake weight for about 15 min and i see that it actually work , the only reason that i rate 4\/5 star be because in the commercial nor in the description mention that it be not battery power . they have to be specific about thing like this . but this product do work , you just have to do the movement . also do not watch the dvd , just look at the popular shake weight exercise and you 'll get it .