This is a water bottle purchased in the 1980s from an outdoor shop in Ochanomizu. It's likely a Markill or a Grantech (the manufacturer is unknown as I've forgotten which). I bought it new and have kept it stored at home without ever using it. The internal coating appears to be in good condition, with no signs of deterioration. I believe this is a rare item nowadays. Please understand that this is a vintage item and accept it with no claims and no returns.