06-13 YAMAHA YZ250F: Fastway Spark Arrestor End Cap (Single) (Black) Fastway designed their spark arrestors as an economical way to convert your stock muffler into a U.S.F.S. approved spark arrested muffler. When the spark arrestor screens are not required, such as at the MX track, simply remove two machine screws on each end cap and take out the screens, it's as simple as that. Each end cap is machined out of solid 6061 aluminum and anodized with a protective finish. Each spark arrestor includes an end cap assembly with: Removable nozzle.