MTX solid discs are constructed using one complete segment of Japanese SUS 420 stainless steel then heat-treated to HRC 36+-2. Lightening and drill hole patterns are as per OEM designs to improve braking performance and reduce the temperature of the disc.MTX Discs provide amazing braking control for your motorcycle. All MTX discs are designed and manufactured with world-leading cutting edge technologies:Precision CNC machined and laser-cut technologyJapanese SUS 420 Stainless SteelReplacement for Original EquipmentOEM Design; lightening & drill hole patternsSpecifications:O.D: 240mmI.D: 100mmMinimum Thickness: 4.5mmDisc Position: Rear Fits: Kawasaki ZR550 ZEPHYR 1991-1998 ZR7/ZR7S 1999-2005 ZX4 (400cc) 1988 ZXR400 1989-1994 ZZR400 1993-2001 ZZR600 1994-2003