What does plastics #1 or #2 mean?

Somewhere on most plastic products you will find a recycling symbol with a number. The symbols used in the code consist of arrows that cycle clockwise to form a rounded triangle and enclosing a number, often with an acronym representing the plastic below the triangle.

Polyethylene Terephthalate (PET, PETE)
Clarity, strength, toughness, barrier to gas and moisture.
Soft drink, water and salad dressing bottles; peanut butter and jam jars

High Density Polyethylene (HDPE)
Stiffness, strength, toughness, resistance to moisture, permeability to gas.
Milk, juice and water bottles; trash and retail bags.

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