SN2-TQZ is a device installed at prescribed intervals on pipelines to detect the passage of a pig or sphere. The indicators function by extending a bidirectional trigger system or Removable Trigger System into pipelines through a Flange Fitting. When a pig passes an indicator, the trigger is tripped which immediately activates a Signaling systems.Signaling systems available with the SN2-TQZ include a flag indicator, a flag/electrical Switch Output or an electrical clock. All are compatible with/all standard Flange Fitting.