Black SWR 130 Standing Wave Meter Short Wave 1.8MHz‑50MHz 120W Digital Disp OU
The green light is on when VSWR is less than 1.5, the yellow light is on when VSWR is greater than 1.5 and less than 2.5, and the red light is on when VSWR is greater than 2.5. The buzzer can be turned off with one key.