The yellow illumination in the actuator provides a clear visual indication of the switch's on/off status, especially in low-light conditions.
The Rocker Switch, On-Off, DPST, Illuminated, Panel Mount, 1855 Series (presumably manufactured by Marquardt or part of the RS PRO range) is a robust electrical control component designed for reliable double-pole, single-throw (DPST) switching in various applications. The yellow illumination in the actuator provides a clear visual indication of the switch's on/off status, especially in low-light conditions.