The AQY212EH comes in a 4-DIP through-hole package (0.300-inch body width, 7.62 mm pitch) with PC pin termination — the same footprint as a standard DIP-4 IC socket or soldered directly into plated through-holes on a single-sided PCB.
Rated for 550 mA continuous load current at up to 60 V AC or DC — this covers low-power signal switching (solenoids, valves, indicator lamps) and isolated data-line switching in test equipment or PLC output modules. The 2.5 Ohm max on-state resistance means the voltage drop at full load is about 1.4 V — acceptable for 24 V or 48 V loads, but for 5 V logic switching the drop may be too high; a lower-Rds(on) PhotoMOS variant would be a better fit there.
The part belongs to the PhotoMOS™ AQY series, a long-running family of MOSFET-output solid-state relays with no pin-compatible direct replacement within the series — the AQY212EH is the SPST-NO 550 mA / 60 V variant in the 4-DIP package.