Featuring Callaway's legendary Big Bertha shaping and A.I. technology, the new Callaway Big Bertha B21 Irons deliver distance and forgiveness, any way you swing it. This is the first Big Bertha Iron designed with A.I. technology, and when combined with Face Cup technology, Callaway has created an iron that produces explosive ball speed and spin robustness off every club in the set. Also new to the B21 Irons is a Visible Tungsten Energy Core, which deepens the center of gravity, making them incredibly easy to launch. Between the core and face you'll find urethane microspheres, which are strategically designed to absorb unwanted vibrations without reducing ball speed. When you add everything up, Callaway has crafted an iron with incredible ball speed and forgiveness, all wrapped in attractive, confidence inspiring, iconic shape.