Strong and sturdy cardboard but also lightweight and can be folded flat. Advanced patented technology ensures that no corrugated edges are visible, the items are completely printable, meet the standards of moisture resistance, and are of course fully foldable and completely flat in its package. - No Tools Assembly. - Waterproof coating. Meets standards of moisture-resistance. - Made of reinforced cardboard recyclable material. - Very strong and sturdy. - Environmental friendly. Free from hazardous substances."