I've had these on my cars for 40 years now. Most racing drivers use them. You always know what's around you.
I think that Ralley, Pilot, Wink, and others make them. When I first bought one from Wink, the guarantee was,
"If it ever fails, we'll replace it." In 40 years, one was parked in a hot car, facing the sun, and got so hot
that the middle sagged 2". I took it to the store, and they gave me a new one.
Mounting is a problem. Neither of their options is any good at all.
I make L brackets that I glue to some inner tube rubber (from hte bicycle shop) and glue that to the windshield.
This is what the mirror looks like from outside the car. It's white, and there is white duct tape outside of the mounts. I've always put brackets on both ends, but for quite a while now, I've had them come loose, so I got a thin wire hanger and bent it so I could clip one end to the top of the mirror, run it behind the car mirror, and clip the other end to the bottom of the mirror. If one end comes loose, that coat hangar wire holds the mirror on. But I may make that my permanemt solution. The reason is that with 2 end mounts, as things heat and cool, there can be strain on the mounts. If there's only 1 mount and that center attachment, then there can never be strain on the mount. I'm still thinking, but that idea is looking really good to me. Inside the car, the mirror goes from one end of the windshield to the other. Sitting in the driver's seat, I have about a 160° field of view behind me. The only real problem I have with that is that, when I don't have the mirror, I forget how much I'm not seeing. There's the L bracket I made, and glued to the windshield. I've always had 2 of them, but I may well switch to just one, and the coat hangar wire to attach my mirror to the car's mirror, which I pull flat down and rest the panoramic mirror on top of it.