Polyethylene (PE) is a thermoplastic polyolefin. It is produced in varying densities and classified as Low, Medium, and High, Densities (LDPE, MDPE, and HDPE). There are other specialty varieties like Very Low Density (VLDPE) and Linear Low Density (LLDPE). Polyethylene can be used in a wide variety of applications from film extrusion, to blow molding, injection molding, compression molding, and rotomolding. It is resistant to most acids and very durable. Wikipedia Link