evo.com | Shimano Rear Derailleurs > Bike drivetrain refresh has a name, and it's Shimano Altus RD-M370, 9-Speed Rear Derailleur. Slap this one on your older MTB and get no-nonsense shifting and chain retention, just how it's supposed to be. Nine is fine! Stronger Return Spring for Crisp Shift Feeling Low Profile Derailleur Cage Reduces collection of debris and potential for damage. Largest Cog 34t Rear Derailleur / Shifter Compatibility All Shimano 9-Speed HG Cassettes, 9-Speed Mountain Shifters, and 9-Speed Chains. Drivetrain Speeds 9 | Shimano Altus RD-M370, 9-Speed Rear Derailleur 2022 - SGS/Long Cage