Why is there a yellow square on the strap of Japanese schoolbag?

That's what students use to reflect light when they cross the street at night. The car lights will glow when they shine on it, indicating that there are students! Your bag is very expensive! We are a factory that processes Japanese schoolbags! Now the schoolbag has been changed! Absolute original order! You can go to Baidu to see (Ji Ya store)! Give it away or return it later! It is good for the growth of children's spine! The price is definitely more affordable than what you bought!