The Shimano XTR M985 rear mech is the future of high end groupsets, with a super low profile design that reduces the risk of damage from those pesky rocks, and a chain stabilising switch that when on will reduce chain slap in rough terrain maintaining more stable drive and help keep the chain on the ring. Features: Full carbon fibre outer pulley cage Cold forged wide alloy links and pivot body leads to lower weight while increasing rigidity Improved cable pull ratio provides a more accurate shift action making the system less prone to contamination and trail chatter Direct cable routing prevents snagging from any trail side hazards Dyna-Sys 10-speed compatible only 35t capacity Medium Cage