New product that perfectly suits my Xperia Z3 compact: hull use with gel, load on USB or with the Sony charger. The magnet is powerful enough (it actually feels when he starts hangs securely on the mobile), but remains a magnetic connection: if you pull the thread, the connector detaches. Here is a magnet that you're not going to suspend mobile! I recommend this product which seems to me of good quality and good value for money and avoids the handling of the sealing cover for charging by USB.
