Introducing Core Blue by Rapport Golf. The perfect balance of high performance, consistency and reliability. Each shaft is specifically designed utilizing our Zone Frequency Profiling technology that optimizes shaft frequency, weight, torque, profile, launch and spin, to help each golfer hit it as long, as straight and as consistent as possible. The Core Blue line has options for every golfer ensuring the right fit. Fit & Design: Designed in 3 distinct weight and flex categories to fit a broad range of player types 100% frequency tested in both 0Adeg and 90Adeg planes to ensure radial symmetry, providing precise, consistent feel and the repeatable performance critical for good iron play Designed using ZFP (Zone Frequency Profile) Technology to optimize performance High modulus material and unique tip structure provide the vibration damping characteristics of graphite with performance characteristics associated with premium steel iron shafts