It has two screw terminals RH and LH on the output side of the relay that should be connected to the green and the yellow wires of the 7 core cable as shown above.

It is a legal requirement when you fit a towbar to provide some form of warning, either visible or audible, to tell you whether your trailer/caravan direction indicators (flashers) are working. For this purpose, a monitoring circuit is built into the TF110R. This detects current being drawn into the unit from the vehicle battery when the trailer flashers are working. When such current is detected, the monitoring circuit generates a signal in the tell tale output, capable of operating a buzzer or a panel lamp.

Although relays emit an electro-magnetic pulse when they switch, they are, for the purposes of EMC regulations, regarded as inert. But when they switch many times a minute, as these do, following the operation of a vehicle's indicators, the frequency of the pulse does contravene some regulations.
Because of this, despite the fact that the regulations hardly apply to our industry, the device has damping circuits or "snubbers" which inhibit such emissions. These damping circuits ensure that there is no question of these relays conflicting with the increasingly complex electronics in modern vehicles.