The safety relays in the SNA, SNO, SNS, SNT and SNZ families feature safe internal logic for monitoring safety functions in industrial machinery up to CAT4/PLe. The SNO4083 is a good general purpose relay, offering design flexibility to MRO and OEM alike. Others are trimmed to specific functions to maximize cost efficiency.
More: http://www.wieland-safety.com/feature/safety-relays/general-purpose