the model FS-1 provides a field-service technician with safe AC power and assured grounding in a single package. It includes AC power protected by both a ground Hault circuit Interrupter (GFCI) and a circuit breaker and also includes an outlet-polarity tester (using agree LED).when snapped to a work surface or mat, it provides a confirmed soft-ground coil cord. Touching a test button flashes an amber LED and sounds a tone if the technician Electric Co., 105 Newton plainview, NY 11803 (516) 420-8990.