FEATURES:

• 4-PIECE CONSTRUCTION
  XXIO 13 Irons feature a remarkably low Center of Gravity thanks to their 4-piece construction, including titanium faces and tungsten-nickel sole weights. That weighting, combined with the Irons' unique Rebound Frame structure which alternates stiff and flexible zones for added ball speed, gives you a satisfyingly high launch with incredible distance.
• TITANIUM FACES
  The thin, high-strength titanium face, along with hollow portions of the heel, allow for an even larger high-density tungsten-nickel toe weight. The toe-side weight optimizes the Center of Gravity location for a higher, straighter launch. In addition to the L-Shaped Groove at the bottom of the Iron body, new grooves in the outer periphery of the clubhead improve face COR for added ball speed and distance.
• REBOUND FRAME
  Rebound Frame uses alternating layers of stiff and flexible zones to enhance overall COR, creating an effect that acts like a spring within a spring. It adds ball speed and distance to every shot. On the Irons, a thinner face flexes more extensively while perimeter grooves etched deep into the interior of the Iron body further enhance flex, especially for shots struck low on the face.
• WEIGHT PLUS
  Our proprietary design positions mass in the butt-end of the shaft, under your grip and behind your hands. This counterweight provides an easier takeaway, helps you find the ideal spot at the top of your swing, and makes it easier to release into the downswing for more consistent contact.
• OPTIMIZED CG BY LOFT
  Progressive variable face thickness optimizes speed and launch for each Iron loft. Long Irons are designed for carry, with a lower Center of Gravity to provide enhanced ball speed right where you strike the face. Short Irons emphasize control, with a higher Center of Gravity for a better high-low MOI.
• Specifications are available here