"Type 13.81 is a low-noise electronic step relay with a width of 17.5 mm and 1 NO closer (SPST-NO) for mounting on a 35 mm rail.
Features include:Use with 3-wire or 4-wire connection, with automatic detection via the relayThe control input can be created continuouslyLonger mechanical and electrical service life and much quieter than electromechanical step relay""Zero-crossing"" load shifting35-mm rail (EN 60715), mounting (13.81)Cadmium-free contact material"