The Titleist DCI Gold OS+ irons take the original DCI Gold irons and add more game improvement features. The OS+ version features a clubhead that is 15% larger than the original DCI Gold set. This increases the size of the sweet spot and increased Moment of Inertia, which means the club will twist less on shots hit off-center to reduce unwanted side spin that cause hooks and slices. Buy the Titleist DCI Gold OS+ irons from 2nd Swing and get a great deal when you trade in your used clubs!