Brake piston: 1.TYPE: 4V4852,7K4937 etc. 2.Material: 45# Steel or others 3.Chromeplate or ... zinc coating Brake piston 4V4852 and 7K4937:1.TYPE: 4V4852, 7K4937, and other types2.Material: 45# Steel or others3 ... us.BUY MLF PART, GOOD CHOICE! Brake piston 4V4852 and 7K4937