The K-Force OS-99 CSI stem is 3-D forged and CNC machined from AL2014. Then it’s combined with a carbon structure using our CSI (Carbon Structural Integration) technology. CSI is a process that permanently bonds carbon to alloy to create a true hybrid product, with many of the benefits of aluminium and carbon. The final details reduce the OS-99 stems weight by using a 4-bolt sculpted AL2014 alloy/carbon faceplate and titanium hardware.