Shimano acera m360 78 speed rear mechacera mountain bike rear derailleur with light action operation and over size pulleys for a wide gear choice features oversize 13 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 teetha 2 yea