ok , so , I have own this product for about 6 week now , and I have be use it on a regular basis . I `` do '' try to work out a few time per week anyway , but , I do not always have that luxury -lrb- due to hectic work schedule -rrb- . anyway , after use the Shake Weight for maybe 3 week , I have start to notice small improvement in the toning of my arm , bicep strength , and overall arm strength . I have no tie to this product , but , I have to say , I really like use it ! I keep use it because it seriously break the monotony in my old -lrb- and boring -rrb- work-out routine , -lrb- which be very important for build muscle -rrb- . I notice that I be use muscle that I do not normally use , from dumbbell & weight alone ... and I must admit , it be fun to use , and you will feel you arm burning after just a few short minute of use this product -lrb- also , a good thing -rrb- . and , YES , there be some `` science '' behind this product . be it the `` be all end all '' of workout ? no ! you still have to eat right , try to live a healthy lifestyle , etc etc. ... but , it be a well construct product , that be fun to use , and `` so far '' seem to be work like they claim . I be usually pretty skeptical when I see something on a tv commercial regard fitness , but , have be into fitness & martial art -lrb- on & off -rrb- for year , I know the science be base on Isometric Contraction , and resistance . it be a proven science and it do work . I do similar excersize when I train in martial art year ago ... only we do not have this type of product back then . yes , there be plenty of negative comment out there -lrb- regard this item -rrb- , but , do not knock it until you have try it . I really think it be kinda weird at first , but , when you start use it , and notice a difference in a reasonable amount of time , you 'll keep use it , which be also very important . my only complaint with the `` Men 's '' version of the Shake Weight , be that it be only 5 lb . would have be a bit better if it be 7 or maybe 8lb ... but , that be just I . maybe they 'll make another model down the road ??? that be my story , and I be stick to it . : -rrb-