Thank you for viewing. This is a set of 4 "Brain Power Activation: Calculation Master" toys from Gakken Toy Hobby. Supervised by Tetsuyoshi Sugibuchi, a master of education, it aims to improve brain power by presenting problems through audio and visuals, allowing you to see, hear, think, and answer. It helps overcome weak areas by repeatedly presenting problems you got wrong, activating your brain by solving problems quickly. Comes with earphones for focused practice. [Product Name] Brain Power Activation: Calculation Master [Supervisor] Tetsuyoshi Sugibuchi [Quantity] Set of 4 [Features] Problems presented via audio and visuals, includes earphones [Manufacturer] Gakken Toy Hobby ★ "Calculation Master" from Gakken Toy Hobby. The key feature is that problems are presented via audio. It's currently a hot topic for "training the brain..." *This is an unused item stored at home. We appreciate your understanding.