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: Honda CBR250RR 1990-1999 NSR250 MC18 1988 NSR250 MC28 1994-1999