It is used to guard access to hazard areas such as press brakes, robotic cells, and assembly stations, triggering a stop signal when the beam path is interrupted.
As a safety light curtain, the key selection parameters are detection capability, resolution, and protective height — none of which are detailed in this listing. The bulk package indicates the unit ships as a single component without accessories (mounting brackets, cables, or alignment aids), so factor those into your BOM. The F3SJ series is a standard-profile light curtain suitable for finger, hand, or body detection depending on the specific variant; confirm the resolution and range for your application from the full datasheet.