FSA OS 99 Stem Titanium Hardware. While carbon fiber is typically the first choice in materials for those seeking to trim every excess gram from their bike, don't forget about aluminum particularly when it comes to stems. The FSA OS 99 with titanium hardware is a superb choice for anyone looking for a featherweight stem that's exceedingly stiff and reliable. Constructed of forged and CNC machined 7050 aluminum, it's everything you demand in a top of the line stem. 64 titanium hardware subtracts even more weight for the mix while the sculpted, 4 bolt faceplate is perfect for carbon fiber or aluminum handlebars.