Polyethylene(PE) and high density polyethylene (HDPE) grates are manufactured through a chemical process that creates a compacted polymer, making them sturdier than other plastics and impact resistant. This also mean that HDPE grates have lower absorption that keep the HDPE grates from cracking during seasonal change. HDPE grates are a win for laboratory settings because the material is highly chemical resistant and able to withstand acids, alcohols and bases easily. PE and HDPE are lightweight and inexpensive compared to metal options. Polyvinyl chloride (PVC) is a popular thermoplastic used for making trench drain grates. UV inhibitors are added to PVC grates to help reduce the effects of weathering by the sun. Polypropylene is another plastic material used in making some of the less expensive and less durable products.