The idea of weight screws in a clubhead has been around for quite some time, the thing that makes the new line of drivers unique is that they're so much bigger and the center of gravity can be manipulated to a much greater degree, therefore you can change your driver to meet the conditions of play....example:\n\nIf it's windy you'd put the weight high in order to give your ball a lower launch angle and keep your ball from being affected by the wind as much. \n\nIt is not a gimmick, it does work, however it is expensive as all getout! So you have to weight that against any improvements you might be in line for. \n\n\nYou can read some reviews of people who have tried it here:\n\nhttp://www.golfreview.com/cat/drivers/taylor-made/PRD_321533_2948crx.aspx#reviews