The XXIO 9 Series iron set features a revolutionary 5-piece club head construction (#4-7) and the newest improvement to Dual Speed Technology which promotes efficiency for the initial portion of the downswing. The XXIO 9 irons have a SUS630 cast body merged with a stronger low-density Super-TIX Plus rolled face and a nickel weight in the sole. In addition, engineers have placed high-density tungsten weights in the toe and heel and the result is a head with the lowest CG in XXIO history and an extremely high heel-to-toe MOI. This 5-piece structure enables the ball to get airborne with ease and further improves the carry distance on miss-hits. The XXIO 9 Series is designed to promote the perfect balance of club head speed and lag for increased energy and velocity at impact. This design improvement to the club creates a higher balance point moving the CG closer to the grip and brings the club head in tighter to the body of the golfer for a more efficient swing.