The GLC-ZX-SM, 1000BASE-ZX SFP operates on ordinary single-mode fiber optic link spans of up to 70 kilometers (km) in length. Link spans of up to 100 km are possible using premium single-mode fiber or dispersion-shifted single-mode fiber. The SFP provides an optical link budget of 23 dB, the precise link span length will depend on multiple factors such as fiber quality, number of splices, and connectors.