FACTORY FATTY: Reminiscent of the works or cone pipe once used by Factory Teams. It shares many of the same characteristics with its craftsmanship and material quality. The Factory Fatty broadens and smoothes out the power curve while boosting gains throughout the entire power band, more low-end, more mid, and increased over-rev. No matter what type of riding you do, the Factory Fatty has the benefits youre looking for. Lighter 20 gauge steel used for the body of the pipe 19 Gauge steel used for the header portion Includes O-rings on most models Hand pounded seams for smooth flow transitions O-Rings included Make Model Year YAMAHA YZ125 05-21 YAMAHA YZ125X 20-22 Fits: Yamaha YZ125 2005-2021 YZ125X 2020-2021