This simplistic designed stainless steel tumbler is not only aesthetically beautiful but is also protected with Biomaster, an Anti-Microbial agent that provides a second line of defence against harmful bacteria. The body and lid are both treated and it’s IN the product, not ON the product which will give you permanent protection. This product is tested in accordance with ISO 22196 for Anti-Microbial effectiveness. Biomaster does not affect the recyclability of the item. The product also includes Verimaster a unique tracer that is built into the material to prove that the item is treated with B