RFL offers two types Fiber Service Units (FSU) for substation or industrial applications, this includes one for protective re-laying that complies to the IEEE C37.94 standard and another for T1/E1 applications. The C37.94 units offer a multitude of electrical interfaces for diverse applications (X.21, V.35, RS-449, G.703 and E1) and are also available with non-standard single mode fiber options.