Callaway Big Bertha B21 Golf Irons – Steel The Callaway Big Bertha B21 Golf Irons in Steel are built to provide the golfer with distance. The iconic Big Bertha shape now has a new and improved formula that enables more distance with increased forgiveness. Callaway’s Big Bertha B21 Golf Irons offer high ball speeds and increased spin robustness from an industry-leading A.I. Flash face Cup. The Ball speed is then even further enhanced by a 360 Face cup which flexes and releases once hit. Callaway has added a significant amount of custom tungsten weighting, yo give the golfer higher and easy launch, while deepening the CG with extraordinary precision, but maintaining high ball speeds. The Big Bertha B21 Irons also feature a club profile that makes use of better shaping. It is designed to give you more confidence over the ball for improved turf interaction. Features & Benefits Fast Ball Speeds From The First A.I. Designed Big Bertha Irons High ball speeds and increased spin robustness from an industry-leading A.I Flash Face Cup. Ball speed is further enhanced by our 360 Face Cup that flexes and releases at impact. Improved Turf Interaction From Legendary Big Bertha Shaping A club profile that’s engineered to give you more confidence over the ball with noticeably wider soles. For an easy launch, lower spin, and a straighter flight, we’ve added more offset into the head. Easy Launch From Our Visible Tungsten Energy Core Now you can get higher launch conditions through the set. We’ve added a significant amount of custom tungsten weighting, so we can deepen the CG with extraordinary precision while still maintaining high ball speeds. Pure Feel From Urethane Microspheres Our patented urethane microspheres comprehensively absorb unwanted vibration for exceptional feel, while also maintaining fast ball speeds.