Fiber Optic Couplers that allow connection of cables. They are like small drums or boxes that receive a connector on each side producing optical coupling with the minimum possible loss. Distributors are used to facilitate weaning and rapid change, coupling the pigtail that has been spliced to the fiber patch cord that connects to the receiving equipment or issuers. Also used to connect a fiber span the measuring equipment. Couplers that one of its ends have the ST connector.