The Ping I15 irons have been designed with the better player in mind. They feature a smaller head than the G15 irons enabling them to be more workable. The irons are a progressive set making them not just workable but easy to use also. The longer irons feature a slightly larger head designed to increase launch & control. The mid to short irons are smaller with characteristics that launch the ball mid to low to give increased control. The new cavity design in the I15 irons feature stabalizing bars & a new Custom Tuneing Port to give a more solid feel & a great sound across the hitting area. This new weighting position created by the CTP promotes the desired launch conditions better players look for. The Progressive head design gives ultimate forgiveness & control throughout the entire set giving you the confidence of hitting much better shots & increased accuracy. A Tungsten weight cartridge has been added to the toe of the I15 irons to help increase the moment of inertia which makes this cavity backed iron more workable also keeping its forgiveness. Ping AWT Steel Shaft: has been designed specifically for the Ping irons. AWT stands for Ascending Weight Technology. Which means the shafts in your short irons are heavier to give better ball control into greens & the the longer irons are lighter to make them more forgiving & increase distance.