like a lot of people here , I see this darn thing on tv and have to check it out . I think two main thing potential buyer want to know be a -rrb- be it junk , and b -rrb- do the darn thing work ? first , `` be it junk ? '' no , it be not a cheapo piece of exercise equipment that will fall apart the first time you drop it . it be actually make of a hard plastic , with metal end . so no , it be not a piece of junk , but rather a pretty sturdy dumbbell . will it last for year ? probably . also of note : the dumbbell do NOT have a motor , run on battery , or shake by itself - that be you job and how you get exercise use it . next up , `` do it work ? '' well , first you have to define `` work '' , which will depend on you fitness goal . if you be look to bulk up you arm , and really pack on the muscle , do not expect one five-pound dumbbell to make you look like the incredible hulk , or the guy in the commercial . it simply will not `` work '' for that purpose . -lrb- suggest  smokin ' hot gun !! : how a average Guy can get Big , muscular arm in one workout a week  instead , what it will most definitely do be provide exercise for you arm -lrb- and other muscle -rrb- , maybe add a little muscle if you be really out of shape , and tone they up . for these purpose , I would have to say that it do indeed `` work '' . I think most anyone who pick this thing up and shake it non-stop for 6 minute would have to admit they feel like they arm have get a little exercise in . sooo , if you be not look to get huge arm , but rather some decent exercise and arm toning - check it out , I do not think you 'll be disappoint .