Sony Portable Reader System PRS-500 Internal Memory capable of storing up to 80 books Integrated Connect eBook online store has over 10,000 titles to choose from ranging all genres and subjects. From classics to best sellers, buy your favorite books. Compact and light weight-weighing Approximately 9 oz without the Soft Cover Up to 7500 Continuous page turns with a single full battery charge Memory Slot for optional Memory Stick media and SD Memory Cards--allows for storage of even more books