Built to offer extremely low friction paired with increased stiffness for loss free shiftingLong tooth profile on lower pulley offers best possible chain retentionLower pulley assembly features a chain catcher to prevent jamsCan be used dependably on or off roadFits SS (short) cage and GS (mid) cage right out of the boxOversized 12 and 19 tooth Kogel pulleysCompatible with Shimano onlyRX800Black