... 4. OEM 5. 32 pages per book Preschool Sound Book This set of audio books including: National Studies, English, Pinyin, Cognitive, ... serve as standard audio books and become the basic audio products withe e pen. Talking pen for the sound books "Preschool Sound Book " The ... attention of the child. We have prepared a lot of sound books, for example , Mathematic , English learning, Classic Fairy Tales , ...