The power behind the LTDx irons begins at the core. A steel core bar centers the CG behind the hitting zone to deliver maximum power to the ball, and is suspended in a soft polymer to maintain exceptional feel. Cobra LTDX Iron Set – Steel. More Flexible For More Speed. The PWR-COR system creates Cobra’s most flexible iron design for increased speed. The construction features a steel core bar that positions the CG behind the hitting zone to transfer more power to the ball. The core bar is fully suspended in a soft polymer to allow the face and sole to flex freely while maintaining exceptional feel. To date, the largest PWRSHELL Face increases the zone of maximum ball speed. The new face cup design features a 23% larger thin area to increase speed away from center, and wraps further onto the sole to promote a higher ball flight. CNC Milled Face And Grooves. CNC milling produces more accurate groove shapes to optimize spin and control for improved accuracy and stopping power into the green.