GRANDLiNK brand multi-functional measuring instrument, model NK200. This compact OPM FLV LAN tester integrates three primary functions into one device. It serves as an Optical Power Meter (OPM) for measuring optical signals, and features a visual fault locator (VFL/FLV) with a red light source for testing optical fibers. Furthermore, it functions as a comprehensive network (Ethernet/LAN) cable testing tool.