The AC-120MD is an AC adapter that's designed for use with these compatible Sony LCD medical monitors only:

LMD-2735MD/2735MC (AC-120MD available as optional accessory)
LMD-2435MD/2435MC (AC-120MD available as optional accessory)
LMD-2765MD/2765MC (AC-120MD included as standard with monitor)
LMD-2760MD/2760MC (AC-120MD included as standard with monitor)

The adapter can operate wherever an AC mains outlet (100-240V, 50/60Hz) is available. It provides a regulated 24V DC output suitable for powering the monitors as detailed above.