The F-MA-FC-FC Optical Fiber Mating Adapter/Sleeve is a wide key adapter used to connect two FC/PC or two FC/APC fibers together with low loss. This model has an FC female fiber connector on each end. FiberLife is here to guide you through the causes of loss in fiber optic adapters and provide optimization methods to help you choose and use these adapters effectively, thereby enhancing network efficiency. What Is Loss in Fiber Optic Adapters? In fiber optic networks, “loss” refers to the. designed for diverse fiber optic applications. The maximum insertion loss is not more than 0.