although I find it more difficult than it look to keep the weight vertical -lrb- and look like the video while do so -rrb- , the shake weight do work and it appear to provide a good workout in a short time . this be a intense workout for a woman whose main arm exercise otherwise be use the mouse or shift gear in the car . however , after use it for a couple of week I can tell that my arm be stronger and more tone , so I be please with the product .