Mizuno mp4 irons in steel or graphite shaft option 21 shaft options plus 22 grip options plus free custom lie and egth options all for one great low price the mp 4 is the purest of forged muscle backs for shot makers seeking the ultimate control over their ball flight a longer softer sense of impact results from the mp 4rsquos bulging muscle design that extends higher up the clubface ndash enhancing the renowned feel of its grain flow forged construction the muscle bulge is most prominen