Pro Circuit's Linkage Arms are CNC-machined from billet aluminum and are designed to stiffen up the initial linkage curve and improve the geometry of the chassis, making the bike much more stable. This will also help eliminate the initial loose and wallowy feel. Turning and cornering capabilities are greatly improved as well. 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. Each link arm includes all of the required bearings and seals. Stock length for the YZ250F/450F is 142.0 mm - Pro Circuit Length is 143.5 mm Fits The Following Bikes: Yamaha YZ250F 2009 and 2014-2023 Yamaha YZ450F 2010-2024