The TaylorMade Burner 09 long-irons, the mid-irons and the short-irons were all designed separately - the goal with the long irons was to bring added forgiveness as well as enhanced distance; the mid-irons were engineered with accucracy and length in mind while the design wizards made responsiveness the key watchword with the short irons.
The TaylorMade Burner 09 long-irons benefit from an increase in the size of the head - the perimeter is expanded, which helps to increase the MOI, while the increased sole wifth means the CG location is low and set back from the clubface.
The Taylormade Burner 09 mid-irons also benefit from an expanded head size, while the short-irons feature a thinner topline than the long-irons and mid-irons.