DIGITAL TEACHING STAMP ROLLER: Our math stamps come in 4 styles (addition, subtraction, multiplication and division), just scroll gently, math problems will appear in front of you, it can print out math problems within 100 efficiently and quickly. REUSABLE ENVIRONMENTALLY FRIENDLY MATERIALS: The math roller stamp is made of durable PVC material and uses the highest quality cuts to ensure a clear impression every time. Dries quickly without fading. With oil-based ink, no acid or lignin, kid-safe,perfect for school/home use. ADJUSTABLE DESIGN: The "Math Practice Number Rolling Stamp" has 10 different ways to queue, and you can change the calculation questions with just the turn of a button. Say goodbye to handwritten addition and subtraction math problems, and use the seal to save you more time. PORTABLE SIZE: The Roller Digital Teaching Stamp is small and exquisite, and comes with a storage box for easy carry. When the ink is used up, you can fill it on the roller side. MAKE LEARNING MATH FUN: Math Roller Stamp can develop your child/student's logical calculation ability and improve the speed and accuracy of oral calculation. As the perfect learning toy, teaching stamps make great gifts for Birthdays, Christmas, Halloween, Thanksgiving and New Years.