I wanted a way to hold my TRN Black Pearl dac/amp on the back of my phone, so I created this! The tolerances are rather tight, so make sure your machine is dialed in. The DAC/AMP is held in 100% by friction, so the more accurate you are the better it stays. My prints hold it tight even when I shake it, but let it go easily when removed by hand. The magnets I used came with a Magsafe Pop Socket, but I'm sure these from Amazon would work. To make a cleaner connection, I bought a 180 USB Type-C cable like this one. I would recommend the 7cm version, but your millage may vary depending on your phone size.