Recycling markets for number 3 through 7 plastics are difficult to find and rarely profitable. Many of these materials were sold to markets overseas until a recent shift in regulations, called Operation Green Fence, was enacted in China in response to high contamination. The value of these markets fluctuates with oil prices as well. When oil prices are low, manufacturing from recycled plastics is no less expensive than from new material. Many communities accept number 3 through 7 plastics in their recycling streams as a convenience to customers, but, when markets are scarce, the materials are often separated and sent to a landfill.