The LED indicator in the rearview mirror will show you the distance from 1.5M onwards to 0.1M. Also there are different lights to show if you are near to any objects. There will also be Bi-Bi sound. Most workshop are able to install. We will give u a list of workshop to go to. Easy to install. For cars with existing sensor, just take out the old sensor and install the new sensor without drilling any holes. It can be quite ugly to drill two more holes as the existing old sensor location is already fixed. Drilling two more holes at the side will make your bumper look weird. Looks better than those reverse sensor with big LCD indicator which needs to be installed on the dashboard and making ugly holes. If you use our one, if you change to a new car, can easily take out. Rearview mirror with led indicator and 2 sensors - $80 Rearview mirror with led indicator and 4 sensors - $90 The rearview mirror with LED indicator is 29cm wide.