Smoke stopper is a simple component - a fuse with connectors, which in case of high current consumption interrupts the power supply and thus protects the electronics. It is primarily used when testing components or during the first connection of the battery to a newly built copter. If you made a mistake during soldering and there is a short circuit in the electronics, the Smoke stopper disconnects the power and ideally prevents components from burning out.
The current for disconnecting the power is 1 ampere. The Smoke stopper is reusable and uses a fuse to disconnect the voltage. The state is indicated by a LED.