Wilson D9 irons have been developed through several tests of different head shapes, all to find the optimal performance for game-improving irons. With a strategic urethane-filled cavity under the sole, you get a high COR and increased ball speed across the whole face. The centre of gravity has been lowered even more than in previous models to give a higher launch angle and steeper landing angle to improve control when approaching the green.
Power Holes technology, Beneath the sole is a strategically-placed cavity filled with urethane foam. These are what Wilson calls Power Holes and they give you an increased COR across the entire face.
Low centre of gravity, The D9 irons have a very low centre of gravity which makes it easy to lift the ball. This makes the clubs forgiving even on poorer connections. From the high launch angle, you get a steep landing angle which increases control in towards the green.