... products withe e pen. Talking pen for the sound books "Preschool Sound Book " The reading pen is a popular ... attention of the child. We have prepared a lot of sound books, for example , Mathematic , English learning, Classic ... own voice to compare with the builtin standerd sound, it is very useful for children to learn ... 3.5 mm standerd eraphone slot;7. Battery, 300 mah high capacity lithium battery.