Callaway Steelhead XR Individual Iron Signature Shape Meets Breakthrough Performance. Steel has long been the dominant material used for making irons, and Callaway possesses unique steel-working talents that have allowed us to create a history of sophisticated designs pairing performance-enhancing technologies with clean, strong shapes. Our Steelhead XR Irons combine the shaping and playability that made the Steelhead X-14 one of the most popular irons of all-time. Their speed and distance come from industry-leading, next-generation 360 Face Cup technology that has helped us become the #1 Iron Brand in Golf. More Speed and Distance from Next-Generation 360 Face Cup Technology Next-generation 360 Face Cup technology increases ball speed with greater efficiency on both center hits and mis-hits for more distance on every swing. Higher Launch and Better Feel from Steel-Infused Polyurethane LayerA bar of steel-infused soft urethane positioned behind.