Golf Clubs Blades or Cavity Backs For Long Irons. Mark Crossfield PGA professional AskGolfGuru asks what is best in a long iron. Mark hits three different 4 irons and talks about how they might help your golf game. Mark hits a bladed,combo and full cavity backed 4 iron and shows you the maximum height with each club. Play bette golf with the correct equipment and let Mark help you understand what might help you to hit more greens and more fairways.