Mountain Bike Right Left Crank Arms Single Crank Ring Set 170MM 104 BCD Aluminum Alloy Bike Crankset for 891011 Speed

104mm BCD.;170mm length for crank arm.; tapered crank arms.;Compatible with 8 / 9 / 10 / 11 speed.;Aluminum alloy material for light weight and strong strength.;Suitable for most mountain bikes.;Come with a 4-bolt chainring.Narrow&wide increase chain retention and wear ,reduce friction and noise.