This Device Can Help Your Kids Learn Math's With Joy! Product Features: 💗Quick and Convenient: With our rotary design, you can easily adjust the column type and choose from 10 different queuing methods and 100 different ways of using the column type. Plus, it's quick-drying and reusable after refilling ink. 💗Save Time and Effort: No more tedious math prep! With our roller stamp, gently scrolling, can efficiently and quickly print out math practice questions within 100. 💗All-in-One Device: Our roller stamp covers addition, subtraction, multiplication, and division, making it a versatile tool for any math lesson. 💗Reusable and Durable: Our roller stamp is small, portable, and can be reused after adding ink. The imprint is clear, and the color doesn't fade or smudge. 💗Fun and Interactive Learning: Our adjustable roller stamp makes learning math a breeze for kids! They'll love rolling out problems and finding the answers. Specification: Material: PVC Shape: Rectangular Weight: 150g Size: 44*30*48mm Imprint: 20*4mm Color: pink, blue Package includes: 1 * Brain Improvement Device for Kids 1 * Bottle of Ink