Prime 9 Technology is a counter-intuitive philosophy based on the less is more theory - it embraces range without adding complexity Intended for use with Box Components` Prime 9 speed group, no compatible with other 11-50 cassettes Similar design as the Box Two Prime 9 derailleur with more affordable materials Glass fiber/nylon composite, steel and aluminum construction Limited slip clutch Stamped inner and outer cage Standard bushing pulleys Direct channal cable stay 9sp 50 Long 2 to 1 BLKUPC/EAN/GTIN: 639266097334