Emergency Transmitter

The emergency transmitter is a device used by heroes to request backup from the Hero Association in emergency situations. According to King, the device is still in its testing stage.

Rumored Monster Arc
Spring Mustachio uses the transmitter to request backup during his fight with Kombu Infinity.

Monster Association Arc
During the fight with Garou, Glasses uses the transmitter to call Genos for aid after Garou defeats their hero group.