Suck-it-and-see mirrors

When I started caravanning, I bought clip on extension mirrors for the car, which were secured by rubber straps. I found they were fiddly to fit on and take off. I now use the 'Suck-it-and-see' mirrors which attach to the car mirror glass with suckers. I think they're great- they have  elastic lanyards to attach them to the mirror housing, just for peace of mind, but they don't get blown off even at 60mph and strong winds. They also have the benefit that they adjust when you adjust the car mirrors using the electric switches inside the car. The only challenge is when the car mirror glass is wet- you do need to wipe it dry before fixing the suck-it-and-see mirror, to ensure that it is securely attached. Anybody else out there like these mirrors?