DIN 41097-4
DIN 41097-4
Steel-tube support for electrical sirens 125 to 500 V<Wechselstrom>; skylightstandard by Deutsches Institut Fur Normung E.V. (German National Standard), 08/01/1968
standard by Deutsches Institut Fur Normung E.V. (German National Standard), 08/01/1968