the Cobra 3400 I/XH Irons are a progressive set with the (3-7) being hollow back and (8-PW) being cavity back. This allows for more forgiving longer clubs and more workable short irons. The Cobra 3400 I/XH Irons are made for mid handicappers who need the forgiveness with long irons, but still want the ability to flight shots with their scoring clubs.
