The?FT-M4XXA sereis are solid state relays containing an AIGaAs infrared LEDs on the light emitting side (input side) optically coupled to a high voltage output detector circuit.
The detector consists of a photovoltaic diode array and MOSFETs on the output side. The single channel configuration is equivalent to 1 form A EMR. The devices in a 4-pin small outline SMD package.