Design Pie Movement Detection Technology Rechargeable 650nm LED Light Electronic Pen for Portable Interactive Whiteboard E-pen is used with Portable Interactive Whiteboard to realize the interactive whiteboard function in any projection area. It isthethirdgeneration of E-penwith built-in lithium battery, no need to change battery any more. Moreover, it has a more useful design of hanging ring, so teachers can hang it on the chest. Its main material is plastic, so it offers more comfortable using experience for users.