Onyx has known plastic and food is an unhealthy combination for as long as you have. It aimed to find materials that are of good quality and not overpriced. They believe that everyone should be able to buy safe and environmentally responsible products without breaking the bank. They have found that high quality food grade stainless steel is the best option for fluid bottles, sealable containers, cups, bowl etc. For it's durability, food safety and versatility i.e. freezer to stove/oven.