The fiber optic pigtails consist of a short fiber optic cable with a factory-polished connector at one end and bare glass fiber at the other. This structure allows for fusion splicing, creating a durable, low-loss connection. The connector end is polished and tested under factory conditions, ensuring low insertion loss and high return loss. Without secure and precise connections, even the most advanced infrastructure cannot function optimally. Key takeaway: Treat the four items like a relay team. By Fiber Type Single-Mode Patch Cord: Core/cladding size:.