My virtual Caravan Site 

Towing Mirrors
(as fitted to my Land Rover Discovery 2)

By law, you are supposed to fit extension mirrors
when towing a Caravan.

Some people still insist that they get a good enough view with their car door mirrors, but, to comply with the Law and common sense you need to fit extra mirrors.
The pictures below should help to demonstrate this

click on picture for full size image

Near-side Milenco Grand Aero flat mirror
Not only do I get a view down the near-side of the caravan, I also get a view, but only in the Aero mirror, of a lorry parked right behind me.

 

Off-side Milenco Grand Aero concave mirror
Almost the same view in both mirrors, but, in the Aero mirror, a view  including the off-side of the Caravan and the mirrors of the lorry parked behind.

 

The big debate is should you fit Flat or Convex mirrors. Well this is a difficult one, and is down to several factors that are dependent on your vehicle and the door mirrors already fitted. I chose Convex to begin with, but was not happy with the result so then I bought one Flat mirror head and after trying it also changed the other one as well to a Flat mirror. Partly the reason was that I have changed the caravan to a longer double axle one, and I find that with the flat mirror it gives me a more precise view especially while overtaking both on pulling out and returning to the inner lane. Also, my car door mirrors are convex and hence I have both views.