The 20.21.9.024.4000 is a 1-pole Modular Step Relay with DC coil, 20.21 series. Single phase switch 1NO (SPST-NO), test button with mechanical indicators. Possible to connect illuminated pushbuttons with the additional part 026.00. AgSnO2, cadmium-free contact. Module for illuminated pushbuttons. 35mm rail (EN 60715) mount.