This two-piece ball has a thin ionomer cover that wraps around an extra-large 1.595-inch core (the largest in the Callaway line). The ultra-low compression ball is the softest of any Callaway model, yet the ball is designed to optimize initial ball speed for a variety of swing speeds. The large core and thin cover produce less spin with the driver, Callaway says, helping initial launch and mitigating hook and slice spin. Quite simply, the results with these Callaway golf balls are amazing. A golf ball this soft, and with this much feel, shouldn't be able to go this far. The new Big Bertha Diablo provides the best combination of distance and feel in a 2-piece golf ball. The new advanced High-Resiliency Core is soft for stealthy feel while also providing wicked distance. The Soft Ionomer Cover with HEX Aerodynamics adds to the feel while also providing longer, more penetrating ball flight for added distance.