HobbyFly Shortsaver XT30/ XT60 Smoke Stopper with Alarm Buzzer,Short-Circuit Fuse
Protection Safety Inspecting for 2-6S RC Quad FPV Racing Drone;
The smoke stopper is designed to avoid damage when you power on a mini quad drone the first time.It is designed with PTC resettable fuse(Fuse can recover by itself ),LED indicator and buzzer alarm.Sometimes you might have a defective part or a short circuit during your drone assembly,the smoke stopper has the over loading current limited and short circuit protection,avoiding "magic smoke" .So you can re-check your drone and replace the bad parts again after test.Figure out what is the problem.
Green LED:Normal situation
LED turns off :Short circuit Or Over loading
Buzzer Beeping:Short circuit
Specification

Dimension:53 x 31 x 11 mm
Connector :XT30 XT60 (Input and Output)
Hold current 0.5A Trip current 1.0A
Input Voltage:7-25V (2-6S)
Note:
The Smoke Stopper is just one of many tools that should be in your electrical kit,It will not protect against all wiring errors.