What does 555 stamped on the bottom of baby cup mean?

The "555" stamped on the bottom of a baby cup typically indicates the manufacturer's identification number or a specific production code. It may also suggest that the cup is made from a type of plastic known as polypropylene, which is often used in food and drink containers. This number can help in tracking the product for quality control and safety purposes. Always check for any additional labels or markings for more detailed information about safety and usage.