On this parts fiche the Washer(10x15x1.5) is the most specified component.
Parts such as the Front Master Cylinder (model K/l/m/n/p/r/s): Washer(10x15x1.5), Union, Union, Hose,front Brake are included in the Rmx250 1989 (k) Usa (e03) Front Master Cylinder (model K/l/m/n/p/r/s) parts fiche.