Shimano Altus RD-M310 7/8-Speed Rear Derailleur

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