Very strong magnet which holds my heavy combination (250g) of Samsung Galaxy Note 9 + stand case without any risk of dropping. I have yet to drive down a rutted back-country road, but so far it seems like it would hold in any condition. Also, the clamp on to the air vent is tight, so it is unlikely that the whole mount and phone will come off the air vent, which has happened with my previous mount. The magnet is strong enough to be effective with the metal plate stuck inside the case. This is despite the Note 9 case being a good 3mm thick, with two padded layers on the back side. Excellent! Love the magnet concept as opposed the the cla...view more