Storage capacity may vary and a portion of the memory is used for data management functions.
3 times as much data is based on actual tests performed by Sony on a sample of 14 files of various types. Compression will vary by file type and content. Already compressed files may not be able to be further compressed. Actual compression may be more or less than 3 times.
Not all products with USB connectors may communicate with each other due to chipset variations.