Singlemode fiber (SMF) has a very small core—around 8 to 10 microns —that allows only a single light mode to travel directly through the cable. Because the light does not bounce around, signal distortion is minimal, enabling long-distance transmission with high bandwidth. HES 8 Core, Single Tube, Steel Armored, Single Jacketed Fiber Optic Cable SM 9/125µ Single Mode HES Brand Fiber Optic Cables HES brand fiber optic cables are designed with high performance and reliability, especially focusing on single mode fiber technology to meet long-distance transmission needs. Good mechanical and temperature performance; 3. In this guide, Omnitron Systems explores the key differences between.