its a ryder unit, which is what i use when fitting towbars
youll also need to power the relay, i take a feed from the rear cig light as its rated at 30 amps, but fit an inline fuse, 15amp inbetween the relay and the cig lighter wire, the live is the red wire or red/white from memory, not brown. the live feed goes into any of the + ports (choice of 2)
the wires from the towing socket go into the relay ports which tell you which colour to put where, the white wire goes to earth (body).