Fiber optic patch cords are designed to connect various segments of optical network cables, as well as to connect them to active network swtiches and patch panels. Patch cords provide high reliability of connection and allowing for re-connection quickly. Fiber optic patch cords are a piece of optical cable terminated on both sides by SC, LC, FC, ST connector types with UPC or APC polishing type. Patch cords can be manufactured using single-mode or multimode fiber. Single-mode cords have an outer protective shell in yellow color, and multimode cords have orange colored protective casing. Optical cords are divided into Simplex and Duplex according to the type of performance, duplex cords are marked with "polarity" connectors, through which users can determine from which connector the light comes out.