I found this on the FAQ page for that *other* ebook reader. <grin> BookCourier supports only type 4 Audible files. The type 4 files are encrypted MP3 files and, therefore, tend to be large. While we would like to support the other file types as well (types 1 through 3), all these files use proprietary compression routines to make the files smaller. The companies who own these routines require royalty payments for their use and decryption. Consequently, BookCourier support for these files types would require a much greater development effort as well as a higher cost to the customer.