The AS6M-21KT2PB is a round keylock selector switch from the IDEC A6 Series designed for 16mm (5/8") panel mounting in industrial control and signaling applications. This switch features a spring return to center function with DPDT (double-pole, double-throw) contact configuration, providing reliable switching for momentary or maintained operations. It is rated for a maximum voltage of 250V AC/DC with a thermal current of 3A and a minimum applicable load of 5V AC/DC at 1mA, utilizing gold-clad silver contacts for dependable low-level switching performance. The switch is available in both IP40 (dustproof) and IP65 (oiltight) protection ratings, with terminal options including .110" solder or quick connect styles. Common applications include emergency stop circuits, mode selection, and equipment control in manufacturing, automation, and process control systems where reliable keyed operation and spring return functionality are essential.