Digital teaching stamp roller: Our math stamps come in 4 styles (addition, subtraction, multiplication and division). Just roll gently and the math problems will appear in front of you. It can print math problems within 100 efficiently and quickly. . REUSABLE ECO-FRIENDLY MATERIAL: Math roller stamps are made from durable PVC material and use the highest quality cutting to ensure a crisp impression every time. It dries quickly and won't fade. Made with oil-based inks that contain no acid or lignin, they are child-safe and perfect for school or home use. ADJUSTABLE DESIGN: The "Math Practice Number Rolling Stamps" have 10 different ways to line up, and you can change calculation problems by simply turning the button. Say goodbye to handwritten addition and subtraction math problems, use stamps to save you more time. Portable Size: The roller digital teaching seal is small and exquisite, and comes with a storage box for easy portability. When the ink is used up, it can be refilled on one side of the drum. Make learning math fun: Math roller stamps can develop your children or students' logical calculation skills and improve the speed and accuracy of oral calculations. As the perfect learning toy, the teaching stamp makes a great gift for birthdays, Christmas, Halloween, Thanksgiving and New Year. Note: Due to the light and screen setting difference, the item's color may be slightly different from the pictures. Please allow slight dimension difference due to different manual measurement. Sold by-Dadangjia