The Society of the Plastics Industry developed a voluntary coding system for plastic containers to assist recyclers in sorting plastic containers. The symbol is designed to be imprinted on the bottom of the plastic containers. The numerical code appears inside three arrows that form a triangle. A guide to what the numbers mean is listed below. The most commonly recycled plastics are polyethylene terephthalate (PET) and high-density polyethylene (HDPE).
| Code |
Material |
Examples |
| 1 |
Polyethylene terephthalate (PET/PETE) |
2-liter soft drink bottle |
| 2 |
High-density polyethylene (HDPE) |
Milk and water jugs |
| 3 |
Vinyl (PVC) |
Plastic pipes, shampoo bottles |
| 4 |
Low-density polyethylene (LDPE) |
Produce bags, food storage containers |
| 5 |
Polypropylene (PP) |
Squeeze bottles, drinking straws |
| 6 |
Polystyrene (PS) |
Fast-food packaging, other packaging |
| 7 |
Other |
Food containers |
