This is a single relay that can be triggered by the MTT Precision Detector. It needs a 12VDC power supply(so does the detector) so we recommend our 12V Power Module.
The Detector Adapter allows reliable triggering of the relay. Sold as a package.
The switch side of the relay has both Normally Open and Normally Closed connections, plus a common. You can switch up to 8Amp/125VAC or 28VDC.
** We DO NOT make this relay and it is readily available elsewhere. We provide it for sale as a convenience. However we tested this one for compatibility so we know it works.