maybe I haven't mastered it yet, but the flex mount tips over easy. I've only tried using it as a stand on a flat surface, so can't speak to how well it holds when wrapping around something
I was hesitant about how well this would work, but I love it and wish I'd gotten it sooner. My phone is very secure with a popsockets brand MagSafe wallet with pop socket on the back.
For the price I think you could find better mounts. It is nice that it works with pop sockets but the mounting angles can be finicky and I don’t feel like it will hold up well as the hinge is already loosening
This is my second one, first one got cooked in a heat wave, my favorite mount. Easy to set up and my phone stays secure. Maybe take it out of your car during a heat wave (the first one was also around 4+ years old.