Connecting Panasonic SF-C10 to the light curtain is done using plug-in connections, which shorten setup and replacement time. A spring method is used for the terminal blocks for connections other than to the light curtain. There is no need to control tightening torques for these terminal blocks. Removable terminal blocks reduce the work required for reconnecting wiring during maintenance. The strong metal enclosure has a built-in safety relay. It has an IP65 protective structure, so that it can be set up individually without the need to be inserted into a control panel. 22.5 mm 0.886 in thickness, so it can even be inserted into narrow spaces inside panels. It is possible to build muting control circuits using a stand-alone light curtain from the SF4B series. The newly-released SF-C14EX application expansion unit allows the light curtain, muting sensors, and muting lamps to be connected together directly, so that muting control circuits can be built easily. Functions that require multiple safety relay units and muting control units can be concentrated into a single unit, which results in large space savings, less wiring, and less installation work.