Graphite fibers come in a variety of stiffnesses and the engineering term for stiffness is modulus. Most golf shafts use a 33 MSi (million pounds per square inch) fiber and call it high modulus graphite. While this is very high stiffness compared to other materials, it is actually standard for graphite fibers. At Grafalloy, fibers with up 100 MSi are frequently used. A 100 MSi fiber is pound for pound 13 times stronger than steel. Shafts such as the ProLaunch Axis shaft have more than 70% of their layup made with fibers in excess of 50 Msi.