The most commonly used material in the world is Polyethylene. Used for almost anything, its price is a major driving factor for its widespread use along with its great chemical resistance and elongation characteristics. It is also known by many different names based on density and branching. Some of those names include: HDPE (High Density Polyethylene), LDPE (Low Density Polyethylene), LLDPE (Linear Low Density Polyethylene), UHMWPE (Ultra High Molecular Weight Polyethylene) and VLDPE (Very Low Density Polyethylene). It also has reinforced products used to help fight expansion and contraction along with providing a better penetration resistance.