The numbers 1-7 are printed on the plastic products to distinguish the types:

1. The first type is polyethylene terephthalate, commonly found in soda bottles.

2. The second type is high-density polyethylene, which is commonly found in hard plastics such as milk bottles, laundry detergent buckets, and plastic dishes.

3. The third type is polyvinyl chloride, including shampoo bottles, shower curtains, hula hoops, credit cards, wire sets, medical appliances, wall panels and pipes.

4. The fourth type is low-density polyethylene, commonly found in shopping bags, compressible bottles, tote bags, clothing, furniture, and carpets.

5. The fifth type is polypropylene, with syrup bottles, straws, Tupperware and some auto parts.

6. The sixth type is polystyrene, with meat trays, egg boxes, clam shell packaging and compact disc boxes.

7. The seventh category is the rest of the categories, including bulletproof materials, vat water bottles and sunglasses. Marking the recycling code does not mean that the material can be recycled, but explains what the material is. Recycling the first and second types of plastics is the most common.