The lunch bag is made of reusable paper - Tyvek which is lightweight and tearproof. The cooler bag interior is padded with thick insulation for keeping food stay cold/warm/fresh for hours. This brown paper sack is soft but extra strong, waterproof and leak-proof, sturdy and durable for storing milk, lunch box, water bottle, etc. Perfect Gift for Adults Women and Men. Large enough for Meal Prep, Everyday lunch to Work or School, Road trips etc