Zipp service course sl stemzipps service course sl stem brings you the technology and quality thats normally reserved for the pros bikes as its best in class stiffness rating results in completely flex free springing and handling ridden to victory at many multiple paris roubaix and vuelta a espaa races the service course sls high quality 7075 aluminium construction and titanium torx head hardware keep the weight extremely low if youre looking to shave bulk from your bike and increase p