AZR Alloy - Undergoes A 3-Stage Thermal Treatment Process. Creates A More Responsive Microstructure That Results In A Better Feel, More Forgiveness & More Performance. It Does All This While Maintaining The Strength Of The Material. One-Piece, All-Alloy Baseball Bat Balanced Swing Feel Features USSSA (New NTS Tested) Certification Stamp 2 3/4 Inch Barrel Diameter