Official Guerrilla Gravity stainless insulated tumblers feature double-wall vacuum insulation. They are 2X heat and cold resistant compared to a normal travel mug and are BPA and lead free. Made from 18/8 gauge stainless steel (18% chromium/8% nickel), also known as Type 304 Food Grade. All finished with a rare, authentic Guerrilla Gravity head-tube badge...one of the last in existence.