The Shimano XTR RD-M950 is a legendary 8/9-speed rear derailleur from the late 1990s, renowned for its "bombproof" durability, lightweight titanium construction, and precise, crisp shifting. Often considered one of the best rear derailleurs ever made, it was part of the groundbreaking M950/M952 group, featuring sealed bearing pulleys for smooth, long-lasting performance.