Decakila vacuum flask Drinking Bottles (KMTT027B) are made with 304 stainless steel, highly resistant to rust and very durable. These flasks have a double vacuum insulation that helps keep the content at a desirable temperature. It is also very easy to clean as it is dishwasher safe and does not need any special treatment to clean it.  Decakila vacuum flask drinking bottles are lightweight which makes them very portable.