The zipp service course sl 6 degree stem was first developed for the fit and performance needs of pros that goal of being pro grade has proven out over the past several seasons as the stem became a mainstay in the pro peloton and cyclocross circuit being ridden to victory in paris roubaix and the vuelta a espana zipp have built on that pro proven legacy with the redesigned service course sl stem this service course sl road bike stem is made from 7075 aluminium and features a redesigned shape