The EPS200 no holes parking sensor is a discrete, no holes in your bumper, Electromagnetic rear car parking sensor system. Compatible with any car or vehicle with plastic bumpers. EPS200 no holes, no drill parking sensor will sense any object, person or car located behind your vehicle, not just metal obstructions. It will provide you with a warning alert system to protect your vehicle from bumps, scrapes & expensive collisions. Designed for people with bike racks, low mounted spare wheels, towbars or other obstables which may otherwise cause false alerts for some of the traditional ultrasonic sensor systems.The EPS200 no holes parking sensor will not start to detect objects until they are closer than the traditional ultrasonic sensors would start detecting, but they will conversely get you closer (about 10cm away) before giving you the final warning to stop. In that respect this is sometimes also considered a better option for someone who is already reasonably competant at reversing and being aware of their surroundings but wanting to use every inch available, when parrallel parking for instance in tight busy streets.