I did not want to start cutting bumpers so this seemed like the best solution, and I was right for once. The kit comes with a hole cutter, adhesive pads, cable ties and a very very very detailed manual. This is not generic far east kit.
The install idea is that you hole cut in the middle below your number plate, stick adhesive pads behind the sensor then push the bar into place. A rubber gromit extends from the centre rear of the plate into the hole, thus sealing the intrusion.
Wiring is simple and all the cables quick connect so you can remove the beeper unit and power cables to aid install.
As a note, I made a clear perspex plate to mount the number plate and sensor bar on, then screwed this into the existing number plate holes, then fed the cable through the number plate light. So not holes at all.
Beeper has two volume settings.