What the part is
The Telemecanique XUSZMD121 is a mirror adapter sold in the Light Curtain Accessories sub-category, used to fold the optical path of a safety light curtain where a straight emitter-to-receiver line cannot be maintained. It carries the UPC 389119618826 for receiving-side traceability, which lets the warehouse and the doc-control file use the same identifier that prints on the carton.
Where it sits in the system
Within a guarding cell the XUSZMD121 is paired with a Telemecanique light curtain pair — the emitter and receiver look at each other indirectly through the mirror, so a single-sided footprint replaces a two-sided mounting bracket when the hazard is on a long or irregular run.