Outside mirror

You actually saw twin mirrors in the US as early as the late 20s, usually topping dual side-mounted spares. Federal Motor Vehicle Safety Standards (FMVSS) 111 (1993) sets performance standards requiring the ability to see both sides of the vehicle from the driver's seat. This means that dual outside mirrors have been required since 1993. I have had twin mirrors on every new car I purchased beginning in 1983. They were standard IIRC.

I agree with Dan that the mirrors are rather small. The other problem with them is that they are mounted close in to the body. As such, it is hard to see past whatever I was towing. They do have some utility value, however.

You may have something like this where you are. http://www.truckntow.com/p-18945-universal-strap-on-towing-mirror.aspx
I've driven a pickup pulling a camper trailer with something like this on it. Good rearward vision remained clear to 75 mph (120 kph). Can't attest to faster because of vehicle was drag limited, would not go faster.
http://www.truckntow.com/p-18945-universal-strap-on-towing-mirror.aspx