Water Proof IP67 Fiber Optic Adapter ODVAWater Proof Fiber Optic Adapters. CFO Assemble all type with most competitive price. Fiber optic adapters (also called couplers) are designed to connect two fiber optic cables together. They come in versions to connect single fibers together (simplex), two fibers together (duplex), or sometimes four fibers together (quad). Adapters…