The PHOENIX CONTACT PSR-MS21-1NO-1DO-24DC-SC is a safety relay designed to be used with failsafe controllers up to SILCL 3, Cat. 4, and PL e. It operates in 1-channel mode with automatic start functionality. The relay provides 1 enabling current path and operates at a voltage of 24 V DC according to IEC 61131-6. It features a fixed screw terminal block for easy and secure installation. This safety relay is an essential component for ensuring reliable and secure operation in various industrial safety applications.