Review on TACKFORM 3-Pack Magnetic Phone Mounts: Stick-On Dashboard Magnet Mount & Cell Phone Holder for Car, Home, & Office by Joe Roberts

Only used one of the three so far but works great. Following the instructions, I first cleaned the surface well, then waited 2 days for the glue to dry before hanging the phone on it. I made sure to place the dash in a smooth and unstructured area (not a lot of open space on a 2015 Tacoma). The phone is fairly heavy, around 6 ounces, with a thick protective plastic case, and there's still plenty of magnet. Traction, no slip at all (it's in a bumpy 4x4 on crappy roads, although I haven't fully "off-road tested" it yet). It's good that they come with extra double-sided tape and magnets (round and rectangular), but they're not needed just yet. No problems with the magnet interfering with the phone yet!