Ritchey Pro 4-Axis 44 Matrix Carbon Stem: 130mm; 84/96d Stainless steel bolts Ritchey 4-Axis stem design enhanced with Matrix carbon/alloy technology 3D-Net forged 6061 alloy is encased in high-modulus carbon fiber for greater fatigue strength Square body shape - stiffer torsionally Matrix carbon/alloy is tougher & stronger than carbon or alloy alone