Pro Circuit's Linkage Arm is CNC-machined from billet aluminum and is designed to stiffen up the initial linkage curve and improve the geometry of the chassis, making the bike much more stable. Although having your suspension revalved by Pro Circuit would make a considerable improvement, the Linkage Arms alone provide a major improvement over the stock set-up. Also helps eliminate the initial loose and wallowy feel. Turning and cornering capabilities are greatly improved as well. Each link arm includes all of the required bearings and seals. Note: Stock length for the YZ125/250 is 145 mm - Pro Circuit length is 146.5 mm.