Altus mountain bike rear derailleur with light action operation and over-size pulleys for a wide gear choice. Oversize 13/15-tooth tension and guide pulleys to reduce noise and wear. Extension spring and low-friction fluorine-coated link pivot bushing result in a light shifting action. Top normal spring for use with Rapidfire shifters. IG and HG chain, 7- and 8-speed compatible. For use with 28 to 34 tooth low rear sprockets, total capacity 43 teeth.