Being a professional backpack brand , all Mountain Wolf backpacks are entitled a free 12 months warranty from the date of purchase . Damages caused by unqualified materials and workmanship are entitled for free maintenance , excluding from natural depreciation and carefulness / improper used , provided by our company . All backpacks return for maintenance are required to present warranty card or invoice in a clean appearance . All Mountain Wolf backpacks cannot wash by machine. It will lose the warranty when it wash by machine.