This is a portable water purifier also used by the comedian Hiroshi, who is known as "Seyshell." I purchased it around spring of this year and used it once at a mountain water source. It has not been used with direct mouth contact. There are no major stains or damage. Please purchase only if you understand that this is a used item. I am decluttering UL and bushcraft solo camping gear. I will consider combined purchases and offer discounts, so please feel free to inquire.