The XXIO9 iron set features the newest improvement to the dual speed technology, a boost in efficiency for the initial portion of the downswing. Lag is increased by utilizing a heavier hear and a lighter shaft with a higher balance point moving the CG closer to the grip. This improvement to the club brings the club head in tight to the body of the golfer for a more efficient swing, which generates more centrifugal force for increased head speed and greater distance.