The Box Four Rear Derailleur is the base of Prime 9 Technology that offers an affordable clutch based 1 by 8-speed derailleur that is simple and lightPerfect candidate for every entry-level bike that traditionally has a 3 by drive-train that is neither durable nor user friendlyFor those seeking an affordable way into the world of 1x drivetrains on an otherwise entry level platformFeatures Box`s Limited Slip Clutch, durable nylon composite knuckle and direct channel cable stayDie cast linkage with stamped inner and outer cage*Compatible with Box Four Prime 9 drivetrain only - Not compatible with other 8 speed drivetrainsBox Four8sp42BlackBoxUPC/EAN/GTIN: 639266097402