The shimano acera rd m360 rear derailleur has been designed to provide you with a light action operation and oversize pulleys for a wide gear choice this rear derailleur is perfect for mountain bikes featuring 7 and 8 speed compatibility for exceptional shifting performance the derailleur features oversized 13 tooth tension and guide pulleys to reduce the noise and wear for great longevity this acera rear derailleur has and extension spring and low friction fluorine coated li