This NOS piston is a genuine original equipment part from Kawasaki, with part number 13001-071. It is compatible with Kawasaki S3 KH 400 A3, A4, and A5 models. The piston is a standard size, making it a perfect replacement for a worn out or damaged piston. With this OEM part, you can be sure of the quality and performance of your Kawasaki motorcycle. Don't miss out on the chance to get your hands on this rare find. Order now and experience the smooth and powerful ride that only a genuine Kawasaki part can provide.