Acera mountain bike rear derailleur with light action operation and over-size pulleys for a wide gear choiceThe Features of the Shimano Acera 8 Speed Rear Mech RDM360 are:Oversize 13-tooth tension and guide pulleys to reduce noise and wearExtension spring and low-friction fluorine-coated link pivot bushing result in a light shifting actionTop normal spring for use with Rapidfire shiftersIG and HG chain, 7- and 8-speed compatibleFor use with 28 to 34 tooth low rear sprockets, total capacity 43 teeth