Heritage-Crystal Clean Inc provides parts cleaning, used oil re-refining, and hazardous and non-hazardous waste services to small and mid-sized customers in both the manufacturing and vehicle service sectors. It operates in two segments, Environmental Services, and Oil Business. The Environmental Services segment offers parts cleaning, containerized waste management, vacuum truck, and antifreeze recycling services, and the Oil Business segment collects used oil and sells recycled fuel oil, as well as engages in the re-refining of used oil into lubricant base oil and by-products. The majority of revenue is derived from, the Environmental Services segment.