As what I have got from Ping I know that with maximum forgiveness technology, Ping Irons provide a variety of design features to lower your scores and help improve your game.
Of course , the G15 Irons also provide the high-launching, maximum forgiveness benefits that the majority of golfers rely on to bring consistency to their iron play. The stainless steel iron’s cavity design features a new Custom Tuning Port (CTP) which expands the perimeter weighting and increases the moment of inertia. Weight savings from a thinner face is re-positioned to the toe for added forgiveness on mis-hits and its wider sole produces a higher launch angle. Stronger lofts combine with a center of gravity located low and farther from the face to produce longer shots without sacrificing the higher trajectory required in a maximum forgiveness iron.
Regarding to performance, g15 irons' new Custom Tuning Port creates a better sound and feel, increases distance, and maximizes forgiveness. Meanwhile, the G15 irons are comically forgiving. So far, Ping had kept its promise: there was a better feel and there was an increase in distance. But how can you dramatically improve a club that you had just a few years back claimed was the "maximum" forgiveness iron? Well,Ping G15 did.
Cheap Ping G15 Irons replace the hugely popular, market leading G10 irons and introduce a number of improvements that make them even more attractive than their best selling predecessors. The biggest improvement is that the wholesale golf equipment G15 irons are a bit more forgiving thanks to the moment of inertia increasing which Ping has achieved by introducing a custom tuning port that is further back from the face of the clubhead. This has allowed Ping's designers to remove seven grams from the G15's face custom tuning port structure without destabilizing the clubface or reducing distance control. This weight is repositioned to move the center of gravity lower and back in the club head to help provide high launch and optimal spin.
The G15 just like its predecessor is an iron that is oversized and designed specifically for players who are looking for maximum forgiveness. There have been several design changes that Ping felt would help to make the club more forgiving.
Here , the G15 irons take the glossaries of Center Of Gravity (CG) and Moment Of Inertia (MOI) as the following :
The Ping G15 irons face is thinner than previous iron models allowing for substantial weight to be added to the toe of the club – this weight redistribution produces a higher MOI which is obviously the name of the game when it comes to forgiveness on off-centre hits.
 The sole of the wholesale G15 is slightly wider in design which also helps to pull the CG lower and deeper which helps the golfer to get the ball in the air.
Features of Ping G15 Irons:
New Custom Tuning Port (CTP) saves 7 grams which is re-positioned to perimeter

for increased MOI
Stronger lofts for increased distance without sacrificing launch angle
Wider sole positions center of gravity lower and farther back for increased launch angle
Weight savings from thin-face design is reallocated to toe for increased MOI.
Investment cast 17-4 stainless steel, heat treated
More information of G15 irons click into http://www.discount-golf-gifts.com/goods-445-Ping+G15+Irons.html .