SHIMANO LX REAR 9SPD REAR DERAILLEUR (M581) TOP NORMAL - The LX rear derailleur uses revolutionary features and concepts featured on XT and XTR at an affordable price point. Wide link design increases rigidity and service life. Alloy body's and outer link leads to lower weight without compromising strength and durability. Two fluorine-coated link pin bushings make this one of the slickest shifting derailleurs on the trails. Top normal spring uses the spring to select higher gears, best suited to use with Rapidfire shifters. Rubber bumper on derailleur body reduces noise and adds to durability.