TG300 TrunkGuard device couplers connect Foundation fieldbus H1 or Profibus PA fieldbus devices in Zone 1 and 2 hazardous locations. The device couplers allow live access for maintenance without de-powering the segment and eliminate the need for expensive Exd/Flameproof junction boxes. Available in 4- and 8-fieldbus models. Special features for Zone 1 and 2 installations include a key-operated magnetic interface that allows individual fieldbus devices to be de-energized and worked on without de-powering the entire segment. Full protection to IP30.