The MO-2 compact, double re-entrant unit with platform base is constructed of heavy-gauge, die cast aluminum to minimize potential damage caused by vibration, shock, impact, dust, wide temperature variations, high humidity, salt water and other rigorous conditions. Its integral compression driver provides optimum efficiency and signal intelligibility. The MO-2 also assures superior sensitivity when used as a microphone for two-way intercommunication. All exposed parts are finished in grey epoxy.