The other trailer thread seems to be losing some posts, so I'll attach another photo of the "Tow-N-See" (brand name) extenson mirrors here instead. As i said on that thread (now missing), it's nice to be able to see the 120,000 pounds of slightly faster semi that is behind you as both of you attempt to pull out and pass a slower moving vehicle in front. Ditto for when the tiny car cuts you off at an interstate entrance ramp and you have to change lanes in a hurry. The boat and trailer is 8 1/2 feet wide and that's wider than anything you'd be towing it with. Standard mirrors just won't do it - you cannot really see whats behind you. Do you NEED it? Probably not. Will it make the trip safer? Definitely YES.
There are other brands on the market, some made specifically for certain vahicles and some for anything. This Tow-N-See works well - never fell of after maybe 10,000 miles of towing big things behind me. The suction cup has a threaded shaft and you turn a plastic nut to create the vacuum holding it to the stock mirror. I'd pick a convex version if available for any of these. Much wider field of view.
Yes - It has a small elastic band that goes around the stock mirror. But, if you clean the car's mirrors first, it's not going to fall off. The suction cup is pulled tight to the glass with a screw thread. They say that the glass will break before the cup lets go. I've used mine for about 3 or 4 years, maybe 10,000 miles and it's never fallen. There are other good mirrors out there too, but this one works well. One good thing about it is that it adjusts with the stock mirror - no need to go outside the car for the right side. Only draw back is that you have to get used to the suction cup mount stuck on the glass. It took me maybe 5 minutes to ignore it when driving.
