ESR bell signals are used for call signals, alarms, or in various other signaling applications. ESR bell signals are also seen in specific hazardous atmospheres such as in chemical plants, oil and gas refineries, bulk loading stations, paint and varnish manufacturing plants, grain processing industries and grain elevators, as well as in certain metal, coal, combustible fiber processing or handling areas. ESR bell signals are also used in conduit systems, and mounted on a vertical flat surface with the striker at the bottom. The conduit hub contains an integral bushing. The body cover assembly permits the location of a hub at the top, bottom or either side (the striker must be located at the bottom for proper operation). There are no external seals required except when used in Group B hazardous areas. The ac signal does not have arcing contacts. Binding screw terminals are provided in ac signals for supply conductors. A vibrating or single stroke striker mechanism is furnished with 6 or 10 inch diameter gongs.