Towing mirrors are some form of extra mirror attached to a car whilst it is towing. Any car with a trailer or caravan behind should have some arrangement of towing mirror to give the extra vision needed. Many states insist on this, but what are the dangers?
The first problem is that towing mirrors are not an integral part of the original car. They have to be fixed on and they can of course fall off. There are many variants of fixings and you need to ensure yours are secure. Some have screw clamp arrangements and some have straps. Some use a suction method to attach to the existing mirror. Some have large scissor-type brackets which give flexibility. Some stick out a long way and others just sit on the existing mirror, but show a different perspective.
Once the mirror is on, will it stay on? Try driving around with it in place. Does it wobble or move in any way? You really must not create a further hazard by having a mirror which will fly off as you reach top towing speed.
Assess the size of the new mirror against its method of fixing. Beware of those which will stick out a long way (so creating leverage) as well as lacking any aerodynamics. If such a towing mirror is attached to your original wing mirror, the force of the wind, amplified by the length of the bracket, could easily close the wing mirror entirely, removing all vision and damaging the car.
Once you have the towing mirror on, be careful if its blind spots. They will differ from those you are used to and you must not forget that the area of vision you now have is different to what you usually enjoy. Towing mirrors are useful, but beware.