Yonex Ezone NS200 5-9,PW,SW SD Iron Set The Double Undercut Cavity and the proven Power Flow Weight System to create one ultimate iron set Double Undercut Cavity increases the size of the sweetspot and the New Sole Construction reduces friction with the ground Power Flow Weight System: A visible weight is positioned towards the heel in the long irons to reduce the tendency to slice, whilst neutral weighting in the mid irons engourages a solid, accurate strike. Proprietary Yonex NS200 shaft for unmatched quality and greater impact speed The short irons have weight positioned towards the toe to guard against hooking the balls.