Image is Representational - See Manufacturer Specs | Safety relay for emergency stop and safety door monitoring up to SIL 3 or Cat. 4 - PL e according to EN ISO 13849 - automatic or manual activation - 2 N/O contacts with dropout delay of 0.1 s to 30 s - plug-in screw connection terminal block The 2981800 is safety relay for emergency stop and safety door monitoring up to SIL 3 or Cat. 4 PL e according to EN ISO 13849 automatic or manual activation 2 N/O contacts with dropout delay of 0.1 s to 30 s and plug-in screw connection terminal block.