this sounder is certified for use in  Atex explosive atmosphere, zone 1 & 2 for gas and zone 21 & 22 for dust. It is dedicated for Oil & Gas, chemical, petrochemical, pharmacy industries, marine and Offshore applications. It’s designed for corrosive environnements and hazardous area. This sounder, according to user control system, can be set with one tone among 59 prerecorded tones. Built in: possibility to select externally (by free voltage switches) 3 tones among the 59 proposed. Pausing of the signal can be done by an external switch . It is possible to control the sounder via a telephone line. Housing and bracket is made of stainless steel 316L covered with UV resistant paint.