the man 's shaker weight do not perform ANYTHNG like the tv advertisement . it be very difficult to get the thing to shake back and forth and do not resemble the tv ad at all . basically , I feel like I have a plastic 5 # dumbell . I be very disappoint in this product . I have a Bowflex and use it religiously 3 day a week . so I be not decondition - that be not the problem . I call customer service and be tell that it do not work as easily as show on tv - keep try .