The 051-0111-203 is a Dialight 378 Series indicator base assembly featuring a diffused red lens cap for visual signaling applications. This watertight indicator base is designed for mounting in a 1-inch clearance hole with front-facing orientation, utilizing an S6 double contact bayonet bulb base for secure bulb installation. The housing is constructed of brass with black nickel finish, while termination is provided via brass solder terminals with hot tinned coating, and the mounting hardware includes a brass nut with white nickel finish and a phosphor bronze internal-tooth lockwasher. Operating voltage ranges from 24V to 250V depending on the selected bulb, and the assembly meets MIL-L-3661C military requirements with a watertight screw-on lens cap design. This indicator base is widely used in ground vehicles, power distribution centers, command and control centers, aircraft cockpits, naval vessels, and surveillance systems where reliable visual indication and environmental protection are essential.