Shimano zee fcm640 m645 10sp single chainringsgenuine replacement shimano chainrings for the zee fc m640 und fc m645 10 speed cranksets 34 36 or 38 theeth featureschainwheel number of teeth 34 36 38fitting for derailleur 10 speedbolt circle 104mmincludes 1 chainring without chainring screwsa 2 year warranty is offered with all shimano products from chain reaction cycles 3 years on dura ace and xtr products buy shimano components from chain reaction cycles the worlds largest online