FEIFAN 31.8mm Mountain bike MTB half carbon stem Aluminum Carbon Fiber Bicycle Stem 90mm 100mm 110mm Material : Aluminum stem with carbon Size:31.8*100amm weight about 150g INSTALL: Pls screw all the bolts slowly . Do not try to screw one of the bolts tightly and screw another.That is not the good way . Fit for MTB bicycle Package include : 1 * bike stem