This Shimano RD-U2000 1x 8-speed rear derailleur's smooth operation low-profile design and dependability will inspire riders to tackle new challenges and expand their trail-riding comfort zone.Optimized geometry and spring tension reduce chain drop provides Stable drivetrain performance on trails gravel and city streetsFeatures Shimano Shadow RD technology that provides a super low profile design that's intended for more aggressive ridingSingle tension construction prevents the derailleur from hitting the chain stay in rough riding conditions resulting is smooth and silent performance45t Min/Max low cog11t Min/Max top cogCompatible with HG 6/7/8-speed chains