MTX floating discs are made from two segments of stainless steel which are riveted together to allow the outer section of stainless steel to expand under extreme temperatures. The outer section is manufactured from Japanese SUS 420 stainless steel then heat-treated to HRC 36+-2 while the centre of the disc is manufactured from steel or alloy. Fits: Yamaha WR250F 2017-2021 WR450F 2016-2021 WR450FSP 2021 YZ125 2017-2021 YZ125X 2020-2021 YZ250 2017-2021 YZ250F 2016-2020 YZ250FX 2017 2019-2021 YZ250X 2017 2019-2021 YZ450F 2017-2019 YZ450FX 2016-2021