The replacement to the popular Viper Ti-Steel Irons, Viper XT irons add extra technology to what was already a super performing iron. Cast with a 431 stainless body, a high-strength steel H420 plate is plasma welded to the body creating a hollow core in the sole and deep undercut cavity. By creating a face that is only supported around the perimeter, it will feel hotter and provide maximum distance from a bigger impact area than most irons. Sole widths are wide, giving the long irons a hybrid-type forgiveness and all the irons in the set are easy to hit. As with many of the other new for 2008 models, Viper XT irons feature 8-gram weight increments allowing for a progressive swing weight set when built with ½-inch length increments. This offers a more consistent MOI (Moment of Inertia) compared to traditional static swing weights.