The Competition Spec 521 irons are maximum distance and forgiveness irons in a traditional cavity back design. The Hot Launch C522 Irons are made with the extremely soft 431 stainless steel, providing the optimal feel for players of all levels.The C Series irons incorporate an expanded undercut cavity to provide maximum forgiveness, power, and consistent performance. The expanded undercut cavity back design delivers an increased repulsion effect for high-speed power off the face and a higher launch angle and enhanced forgiveness.