This 64GB USB3.0 Key Works perfectly with my car stereo Sony CD / MP3 / USB / Bleutooth MEX-BT3900U. I put MP3 and WMA file and read everything impeccably, no song stutters. It is formatted by default with exFAT 128Kilo-byte allocation unit size. It can also be set NTFS (but will not be recognized by the unit). A small red LED lights when the key is active. For warmth, say it is warm (from the first 5 minutes and stays warm) because further notice saying that the key is boiling limit of not taking with unprotected hands. (At least not mine It is and remains warm). For speed I copied 8GB (95 Folders and Files 1979) MP3 and WMA to +/- 6 min.
