Thanks for the question. We were surprised as well with the Nike Viper series of irons, especially after their advertising talked about “moving the center of gravity closer to the center of the club”. Guess that tells us it was not in the center to begin with. Anyway, based on our measurements, the cg’s on all three models were slightly toward the heel. Not much, but they were not in the center of the face. Please understand, just because they are rated in the Player Classic category does not mean they are bad irons. It just means it would take a really good player to get any kind of benefit out of the iron, because they would not be considered very forgiving. The measurement(s) that hurt the rating on the Vapor Pro and Vapor Pro Combo was the C dimension (hosel centerline to horizontal location of the cg). Both were less that 1.2 inches, which is short. Shorter dimensions mean less stability on off center hits. The vertical cg’s were not as low as they could have or should have been, which also affected the rating. The Vapor Speed’s actual vertical cg was way high 1.010″, so even though it had a high MOI and a C dimension over 1.4″ (which is good), the actual vertical cg was aver 1″! When you consider the cg of a golf ball is .840, driving the cg of that iron below that of the ball might be a challenge. Good looking irons, but when you consider playability, you have to look beyond the appearance and consider the mass and dimensional characteristics and how they affect the playability of the design.