Within each chasing arrows triangle, there is a number which ranges from one to seven. The purpose of the number is to identify the type of plastic used for the product, and not all plastics are recyclable or even reusable. There are numerous plastic-based products that cannot break down and cannot be recycled.

Understanding the seven plastic codes will make it easier to choose plastics and to know which plastics to recycle. For example, water bottles that display a three or a five cannot be recycled in most jurisdictions in the US. A three indicates that the water bottle has been made from polyvinyl chloride, a five means that it’s been made of polypropylene, two materials that are not accepted by most public recycling centers.

Here are the seven standard classifications for plastics, and the recycling and reuse information for each type.