704.602.0 Lens, Round, Black, 04 Series. The EAO Series 04 snap-action switches are renowned for their attractive design, superb tactile feedback and reliability. With low profile flush mount options they enhance the design of vehicles, trains and machines. These snap-action switches have a modular design with a range of actuator type’s that include; indicators, pushbuttons, selectors, keylocks, emergency stops, potentiometers etc. providing operator panels that are innovative, intuitive and reliable.