The new Acer XK hybrids are based on the most popular hybrid platform in the Acer line. However, a few new design elements have been added to further improve upon the performance. First, Acer incorporated a variable face thickness to reduce the perimeter area of the impact area so the entire club face could be more active. This acts to increase the area of forgiveness over a larger portion of the face. Secondly, the crowns were constructed with exclusive VCT (variable crown technology) that measure as little as 0.5mm thick. All the unwanted weight normally reserved for the crown was repositioned deep within the head for added stability, feel and added trajectory to hold greens better. Length and lofts were selected to be exact replacements for the same numbered long irons in terms of yardage.