The CA 1242 switch is used with the built-in and under the table mounted microphone units of the MCS 50 discussion system. Optical and functional aspects play an important role for the selection of an external button. This is the reason why the use of the CA 1242 with an integrated dual-coloured LED ring (red/green) is recommended. The CA 1242 is suitable for the Push-To-Talk mode (PTT) of the microphone units. The CA 1242 switch has a mounting diameter of 30 mm and provides almost no mechanical parts. Therefore, the switch is not subject to mechanical wear and tear and can be operated silently with a gentle tactile response. The rugged alu coloured metal housing is insensitive to shock and completely sealed up so that dust, dirt or liquids cannot harm the switch.