... in high noise area such as engine room;4. Send/Receive Display:Display for sending,receiving,voice enhancing. Main technical ... Flashing and bell unit contact: 2A/DC 24V;4. Power supply:DC24V+30%,-25%.Our product is ... levels:forehead 1,forehead 2,forehead 3,forehead 4,stand by ,stop,finished,astern 1,astern 2 ... ,tern 3,astern 4. Order error alarm:When the forehead or astern ...