It reports as a 500 GB drive to the computer and you can copy small files to/from it. But it's basically a ring buffer; once the actual (much smaller) capacity is full it goes back to the beginning and starts writing over the earlier data.
Heh it actually had zero capacity, or rather functionality. You could successfully move gigabytes of data onto the thing and when probed it would report back that it had like a 58 GB partition, but then you could not access any of those files. It was using some sort of custom controller to mimic a legit file system but I don't recall the complete details, just that there was definitely no flash memory chip on the PCB. I have it stashed away somewhere, I should dig it up do another analysis.
Out of curiosity (if you remember), what was its actual capacity?