This is a Noyafa NF-604 Halogen Gas Detector, a handheld device used to locate leaks in HVAC and refrigeration systems.It features a flexible 250mm probe for reaching tight spaces and a digital screen that displays gas concentration in parts per million (PPM).The detector includes visual, audible, and vibration alarms to alert the user to leaks.It is designed to detect all halogen gases, including chlorine and fluorine, with a detection range of 0-1000 PPM.