From Golf Magazine (December 2009)
The base construction is similar to its predecessor but the feel properties have been tweaked to block out lower frequencies (which create a harsh feel). Updates include the aluminum badge backed by soft elastomer in the cavity (which elicits a soft yet solid feel). A 55-gram tungsten-nickel sole weight further enhances feel and forgiveness. Short irons (7-iron to PW) have less bounce on the back edge of the sole, for crisper contact. Stock shaft is Dynamic Gold (original AP2 had Project X).
• The Shop blog: Titleist pros and clubs
• More on the Titleist AP2 irons: titleist.com