The Techlogix S1-LC-F-ST-M is a Fiber Optic Adapter, Simplex Single Mode Female LC to Simplex Male ST. Fiber couplers (sometimes called adapters) are a simple and stable way of extending your fiber optic cable, or creating a service point at a patch panel. They are also great for coupling your bulk fiber installation cable to a patch cable which will increase the longevity of the install cable.