A functional masterbatch is a concentrate of additives used to improve the performance of HDPE polyethylene during processing and/or end use. The most common types of functional masterbatches are those that contain anti-fogging agents, slip agents, and anti-blocking agents. Other types of functional masterbatches include those that contain UV stabilizers, antioxidants, and other types of additives. The choice of additive(s) used in a functional masterbatch depends on the type of HDPE polyethylene being processed as well as the desired final properties of the finished product.