This essential tool lights up a green LED to indicate a secure connection, while potential electrical hazards during inspections XT30 & (Input and Output),suit for FPV with XT30 or connectors This Smoked stopper can help avoid damage when you power for the first time It protects your electronic components from power surges and gives you the opportunity to fix the fault without having to replace the blown part The LED indicators turn solid green in normal situation, The LED indicators turn and starts beeping in abnormal situation