According to the port's type can be divided into several categories as follows:
SC fiber optic attenuator: applying to SC fiber interface, and RJ-45 look very similar, but SC interface is a little bit flat, for the obvious differences are the contacts inside, if 8 thin pieces of copper, it is RJ-45, if it is a copper cylinder was SC fiber-optic connector.
LC fiber optic attenuator: used in LC fiber-optic interface, connector attached SFP module, it uses easy modular Jack (RJ) made the latch mechanism. (Router)
FC fiber optic attenuator: used in FC optical interface, external strengthening is a metal cover, fastened to the TURNBUCKLE. In ODF (with rack use the most)
ST fiber optic attenuator: used ST fiber interface, used for optical fiber distribution frame, oval shell, fastened to the TURNBUCKLE. (10Base-F connections, connector type usually ST. Often used in optical fiber distribution frame)