Single Mode Simplex Fiber Optic Adapter, Plastic, 0.2dB Insertion Loss Fiber optic adapters, or fiber optic couplers are used to terminate or link the fiber optic cables or fiber optic connectors between two fiber optic lines. By linking two connectors precisely, fiber optic adapters allow the light sources to be transmitted at most and lower the loss as much as possible. Each fiber optic adapter is individually and rigorously tested and certified under drinia.tech fiber optic inspection processes to make sure low insertion loss and good interchangeability and re-producibility.