I somewhat regret not heeding some of the advice given by other reviewers on here. This product works very, but I found the resistance to be a little on the weaker side. I suppose it depends on what you're looking for. If you just want to strengthen your wrists a little, this product works fine. But if you really want to build up your wrists and forearms, put in the extra money and buy something better. This product has low resistance and is not comfortable at all to use for extended periods of time. The grips are pretty cheap (foam) and slip and move under your hand.
Take-home message: For the occasional user who isn't too set on quality, get this product, it's a good bargain. Otherwise, keep looking.