Made of 4 mm MDF (Medium Density Fiber) It is more durable. Anti Rust Metal Clip strong high grip clip, has been used. Printed and Laminated, which would make it Water Resistant. Can be used for any purpose, exam or drawing or writing, or office use. | Strong Holder: Strong and Smooth Clip Holder which holds your documents, papers, Notes tightly. Perfect Size for Every A3 size Full scrap Document, Painting, Drawing, any project.