In general, steel case does not rust, but everything is relative. There are many types of stainless steel. Sweat discharged from the body contains hydrochloric acid composition, the table worn on the hand, if long-term erosion by sweat or acid-base salt dirt accumulation without wiping, the case will slowly appear rusty, especially in the low back cover comes out often. Therefore, usually watch watch should pay attention to maintenance, often wipe dust on the case, sweat and so on. In addition, we need to avoided strong acid, alkali and other occasions wearing watch operation, so that the case will not appear rusty easy.