Catching eels (2)

While the two of them headed to the Yu house, Yu Dong took out two brooches and handed them to Yu Mai and Lang Ru. 

She said to them, "Wear these with you every time you step out of the house, these will protect you." Yu Dong had given the kids a bracelet to protect themselves but the children needed to press a button to turn on the mechanism. 

In times of danger, children as young as Yu Mai couldn't remember to press the button of his bracelet.

This is why Yu Dong looked long and hard to find these brooches, at least these were different from the bracelet and didn't have a button that needed to be pressed to activate the mechanism. 

Instead, these brooches would keep a close eye on the heartbeats of the children as long as Yu Mai's heartbeat remained the same nothing would happen but in case his fear reached a certain degree this brooch would protect him.