Wossner is Germany's finest aftermarket forged piston and rod manufacturer and have over 25 years of experience in the high-performance racing industry. Top European racers and FIM World Champions rely on Wossner for only the best pistons, rods and customer service.Features In-house designed and manufactured; all forgings are produced in Wossner's company-owned forging operation 4-stroke pistons are made using a double-bridged forging design Lightweight pistons with the tightest piston-wall clearances in the industry give you a quieter running engine All pistons include piston, ring, wrist pin and pin locks Wossner pistons are used by leading Supercross, Arenacross and MX GP teams Made in Germany Specifications Piston Size: 66.35mm Oversize: Standard Number of Rings: 1 Replacement Rings: RSB6640 Replacement Wrist Pin: WP033 Replacement Circlip: CW18 Replacement Needle Bearing: N1021 Fits: Yamaha YZ250 1999-2005 2007-2008 2011 2013-2015 2017-2021 YZ250X 2017 2019-2020