DURÁN toxic, explosive gas and oxygen detection control unit, 2 zones, expandable to 4 zones. industrial use, up to 16 detectors per zone. 4 ventilation groups. 4 relay outputs per zone, compatible with analogue and rs485 detectors. lcd display, visual/audible indications and self-configuration of detectors/gases. can detect up to four different gases (toxic, explosive or oxygen) simultaneously. remote relay modules and 4-20ma to rs485 conversion modules.