Multi-function Business Card Holder + Solar Calculator + Ball Pen. No battery needed! The calculator will work under sufficient light (sufficient enough to read a book). It’s an 8-digits calculator with memory calculating function: M+,M-, MRC. There is a mini ball pen attached – writes in Blue Ink. It’s also a biz/name card holder; the card will be in or out by rolling, AMAZING! Perfect for home and office use.