The SICK WLL12-B5171 is a fiber-optic amplifier/photoelectric proximity sensor designed for short-range detection using plastic fiber. It features a rectangular zinc die-cast housing with IP67 protection and a visible red LED light source. Adjustment is done via a potentiometer. The sensor supports both light and dark switching and connects via a 5-pin M12 male connector. It operates reliably in industrial environments and is suitable for precise proximity applications.