Q4 HEX: FMF is the leader in high performance quiet technology and the Q4 HEX is the next evolution in offroad exhaust. The Q4 HEX silencer employs intricate chambers, baffles and proprietary multi-stage packing material making it the best performing quiet muffler available. With the Q4 HEX you dont need to hear the power, just feel the power! Less sound equals more ground Meets USFS and FIM World Enduro sound regulations Power gains throughout the entire RPM range Spark arrestor included Pounds lighter than stock Rugged design for off-road endurance FMF is the only US manufacturer to offer dedicated quiet exhaust systems MADE IN THE USA We recommend all motorcycle parts are fitted and tested by qualified professionals. Fits: Yamaha YZ250F 2019-2021 YZ250FX 2020-2021