Resin identification code
A resin identification code (RIC) is a symbol embedded on plastic products, used to sort plastic waste for recycling. They consist of a triangle of clockwise "chasing arrows", around a number indicating what type of resin it is made of (01 for PET, 02 for HDPE, 03 for PVC, 04 for LDPE, 05 for polypropylene, 06 for polystyrene, or 07 for Other).
Source: Wikipedia — Resin identification code (CC BY-SA 4.0)