4 - Glass Base, Frosted Glass, 12 Volt, 1.2 Watt, Instruments, Switches and HVAC Control Illumination Bulbs.
This bulb is 5mm in diameter and 20mm tall with a white plastic base.
This bulb was used in the headlight switch, heater and A/C switches, instrument illumination, dash gauges and other uses.
There is an alternative bulb with 0.5 wattage EPSSB-2, see the illustration, however this is the recommended one from Mercedes-Benz, for this application.