Why do two drives appear when I insert the Vision 1000 SD card into my computer’s card reader?

The Vision 1000 embedded software contains the Appareo Virtual File System (AVFS). One drive on your computer represents the physical SD card and the other represents AVFS (assigned to drive M or later). Raw, unpartitioned data is recorded to the Vision 1000 SD card. AVFS converts the raw data into viewable flight data based on when the file was recorded and what type of data is represented. For this reason you can only access and use data from the AVFS (instead of from the physical SD card drive).