The Siemens 3SF5803-4DC00 is an encapsulated pushbutton unit that combines a clear indicator light with white and black pushbutton plates. It's a single-component assembly meant for panel-mount applications where space is tight and the environment demands a sealed front end — the encapsulation keeps contaminants out of the switch mechanism.
Encapsulated pushbutton enclosure with a clear indicator light (C=), a white pushbutton plate (B=), and a black pushbutton plate (I=). The trailing 0 denotes the contact configuration or actuator variant.