Cobra Golf Fly-Z XL Iron Set 4-GW Steel Speed Channel Facein Irons: An engineered trench behind the face area helps to minimize face thickness and increase flexion Dual Cavity Hollow Design: 4-8 irons feature a dual cavity to create a lower & deeper CG that delivers easy launch with extreme forgiveness Perimeter Undercutting: (9 - SW)-Removes weight from the back of entire face area to create a large undercut for forgiveness in scoring irons