The 861SSR115-DD is a Magnecraft? Solid State Relay with SPST-NO contact, DC switching mode and screw terminals. This 861-series DIN-rail mount relay features solid state circuitry involves no moving parts which extends product life, increases reliability and enables silent operation. Optically coupled circuit provides isolation between input and output circuits. Internal snubber helps protect the relay's internal circuit from high voltage transients. Internal heat sink provides factory-tested thermal management. Fingersafe? terminals helps prevent an operator from touching live circuits. DIN-rail mounting provides flexibility to accommodate last minute design changes.