Srixon’s ZX5 Irons combine pioneering ball speed technology with premium forged feel, and delivers all of it in a forgiving yet workable chassis that’s razor sharp at address. After thousands of iterations, Srixon's automated intelligent design software produced MainFrame. This unique design consists of milling a variable thickness pattern (made up of grooves, channels and cavities) into the back of the iron's face. After two years of refinement, these faces offer greatly improved COR because they maximize flex at impact.