As with all Senitrus devices, there is a microSD card slot. This slot is for your personal files as your personal files will not load on the OS/Apps drive. If you don’t have a microSD card, then you would not be able to store any books on your reader. In the case of the eInk devices, this microSD card card slot is for your ebooks, and audio files. Now, someone might suggest to just increase the OS drive, and allow storage on that drive. However, what will happen if you have personal handwritten notes on your tablet, and your device fails you. You can’t simply take out the storage, and return the device for repairs. With your personal files storing on an microSD card, you can remove the card, send your device for repairs, and receive your device. You will then reinsert your card into the returned device. You lose no files, and just been inconvenienced by not having your reader, or tablet with you.
Senitrus will provide a 64GB? microSD card with the purchase of the device. This allows you to store 64,000 books, or fewer books with audio files. It is quite possible that you would not need to invest in a microSD card. If you have a Senitrus account, you can backup your personal files to Senitrus Drive, or another option will be to copy your files to a NAS?. Since the ebook reader will be running on a version of Senitrus, it will be easy to backup to a NAS without taking your card out of the reader.