Utilizing a three-stage thermal treatment process, our new AZR alloy offers a more responsive microstructure for better feel, more forgiveness and more performance while maintaining the same strength as its predecessor One-of-a-kind, OLS, Outer-Locking System, attaches the barrel to the handle from the outside in, creating the stiffest connection available, while dismissing virtually all vibrations on contact for the strongest, smoothest swing yet Multi-variable wall design creates an expanded sweet spot and thinner barrel walls that are more forgiving after off-centered contact Ring-free barrel construction allows for more barrel flex and increases performance with no "dead" spots Power-loaded barrel results in a higher M.O.I. and end-loaded feel for effortless power.