Hand wash tumblers with warm water. They are not dishwasher safe. Handle with care. Do not soak. Do not drop. Not microwave or oven safe. Do not leave in extreme temperatures. Can be used with hot or cold. Tumblers are stainless steel. Your cup was Handmade with Love and attention to detail, Please be aware that all handmade items may contain small imperfections. Please handle with care.