If you are still looking for a practical tool to learn match addition and subtraction, please take at this product. Our product is a fun roller math teaching stamp with inks. It can be adjusted, and the questions can be changed by gently twisting the button. It adopts add and subtract within 100 numbers to solve the problem. Simple questions are easier to understand. Features -Color:Pink -Material:Plastic, Ink -Size:7.00X6.00X3.00cm/2.75X2.36X1.18in is clear, the color will not fade after drying, and it is not easy to smudge. And it can be refilled with ink and reused. This stamp is equipped with ink, which can be used on most paper and is not easy to fade. The roller digital teaching stamp can efficiently and quickly print out math exercises to cultivate logical calculation ability. The roller math stamp is suitable for practice, parent guidance, teacher teaching, stationery and teaching supplies. With the help of this addition and subtraction teaching rolling math stamp, your little one will love it and love math. Package list: 1 x Math Roller Stamp 2 x Bottles of Printing Inks