This Coroplast panel is made of corrugated polypropylene material. This construction is very similar to the way heavy cardboard box material is made, but with polypropylene (plastic). It is 100% weatherproof, lightweight and a very tough ridged material. Uses include: laminating, taping or tacking posters or other fliers. It also works great for vinyl lettering or as a marker board when used with our liquid chalk markers. This panel is reversible, so you always have a fresh side.