I received this product earlier this week, it seemed used since there was no plastic packaging. When connecting to the Mac mini 2012, the disc is not recognized, by disconnecting and reconnecting the USB (3) the disc is mounted on the desktop. On rebooting the computer has not turned the disk. Thinking of a failure of the device I've sent it to me at Amazon has taken no problem and sent me back a new product. Even symptom product but in addition, the disc may not be read properly. I tried on the MacBook that's him in USB 2 and the problems are similar. I highly recommend this product to Mac owners.