Titleist is behind the legendary golf iron engineering called DCI, which stands for Direct Central Impact. It maintains important design elements in a classic iron, yet offers game improvement. Titleist DCI Irons were first introduced in the early ’90s.
What difference do Titleist DCI irons make? To start with, the definition of impact is the collision of one body against another. A straight line that is perpendicular to the plane of contact of two crashing bodies is called the line of impact. 
Direct Central Impact happens if the centers of gravity (CG) of the two bodies are on the line of contact. Direct Central Impact gives highest energy transfer between two bodies. The DCI iron is intended to align the center of gravity of both the golf ball and clubhead at impact for longer, straighter shots.
The center of gravity is a single point on a clubhead. When this point is lined up with the golf ball at impact, the clubhead will defy bending, resulting to a solid shot. If you position the center of gravity on every iron head in an exact location, it will maximize energy transfer and produce optimum trajectory and backspin.
The shape of the cavity of the Titleist DCI irons is different from most golf clubs. The shape of each cavity is established by the amount of the removed weight, one gram after another. It starts from the heel, then to the toe, top and sole of the iron, in order to find the CG at the center of the face. In long irons, the weight is focused near the base of the toe so the golfer will get the ball up in the air. The weight allocation in middle irons is neutral, while the weight in short irons moves higher in the toe so it can create a flatter trajectory with maximum backspin.
The sole of Titleist DCI irons is radiused in two different directions. The heel-to-toe sole radius helps in preventing the clubhead from experiencing bends in tight lies, and the front-to- back sole radius guides the club through the turf. The leading edge and trailing edge are slightly arced to reduce drag at takeaway and impact.
The first model of Titleist DCI irons is the DCI Gold, which was created in 1991. It was a gold delta that had a moderate progressive offset. Other models were the DCI Black, DCI-B, DCI Oversize (available in Senior, Lady and Oversize Plus), DCI96, DCI962, DCI962B, DCI981, and DCI990.
