Az4x alloy construction provides increased strength and a higher response rate. One-piece alloy construction provides a clean, consistent, traditional feel More responsive, optimized barrel design creates a sweet spot twice as large as the Cat6 2nd generation Av2 anti-vibration knob features an upgraded, finely tuned harmonic dampening System for better feel and less negative vibrational feedback Engineered barrel-end wall thickness profiles improves balance and allows for faster swing speeds 2 5/8 inch barrel diameter, USSSA 1.15 bpf Certified.