I be encourage by read the positive review , so I go ahead and order one , think it would be beneficial . I have no idea how anyone could have they arm become sore from this device . I use it 2-3 time a day for 5 day , and feel absolutely nothing . I be not in primo shape by any means , but a 2.5 weight be not go to help most people improve and tone they arm . what a waste of money .