Build longer 100 GbE links without changing the shape of your switching architecture. The 100G ER4 lite QSFP28 40km module is designed for single-mode fiber deployments that need extended reach, LC connectivity, and the port density of QSFP28. It is a strong fit for backbone links where distance matters as much as throughput. This optic is specified for 30 km without FEC and up to 40 km with FEC, giving architects flexibility when planning between buildings, across campuses, or into metro aggregation points. That reach makes it more suitable than short-reach optics for distributed environments, while the QSFP28 form factor preserves switch density and keeps cabling straightforward. For teams standardizing on 100 GbE, ER4 lite optics help avoid overcomplicating the design. You get long-distance transport, LC-based patching, and a module class that fits enterprise backbone requirements without forcing a redesign of the physical layer. It is the kind of component that earns its place in networks where uptime, distance, and bandwidth all have to align.