A Sounder Beacon is an alarm which has both audio and visual properties and which is usually used in emergency situations, such as fire alarms for evacuations or on emergency vehicles to alert road users. The Sounder emits a loud audible alarm to raise alert to a hazard, while the Beacon provides a clear visual alert - usually by a flashing indicator light through a coloured lens. Conventional Sounder Beacons are often used in commercial and industrial sectors and can be found in public places such as schools, warehouses, offices, construction sites, laboratories and industrial parks.