This kit is designed to have 4 sensors fitted down 1 side of the vehicle this can wither be on the Left or Right side as can be set using the dip switches on the ECU.
Here is a list of each part available as a Spare
ECU - 0-870-92
SPEAKER - 0-564-60
MAIN HARNESS - 0-870-87
SENSOR HARNESS - 0-870-90
SENSOR 1 - 0-870-991
SENSOR 2 - 0-870-992
SENSOR 3 - 0-870-993
SENSOR 4 - 0-870-994
2M CABLE - 0-870-91
3M CABLE - 0-870-86
BUZZER - 0-870-89
GPS Antenna 0-870-85
Links for manual and wiring diagram below