The Triplett ETFB10 combines a Non-Contact AC Voltage and a Optical Fiber Detector. It has a 50 to 1000V AC voltage range with high sensitivity that allows it to detect low voltage AC wiring (50V) commonly found in low power systems, process controllers, garage door openers, power relays, coils, alarm sensors and controls. In addition, you can quickly determine the presence of optical fiber activity for single and multimode fiber, patch cords and ports. It features a built-in worklight in the tip, flashlight in the back, low battery indicator (<2.4V), and auto power off after 5 minutes. CAT IV 1000V safety category. Includes (2) AAA batteries. 1 year warranty.