2PCS Smart Math Roller Stamps for Kids,Addition and Subtraction Practice Stamps and Fill in The Roller Stamp Within 100,Math Roller Stamp for School Teaching Supplies.【2 Pack Digital Teaching Stamp】：Addition and subtraction math stamp, addition and subtraction within 100, can be adjusted flexibly. 【Interesting School Supplies】:The set includes 1 addition stamp, 1 subtraction stamp, and 2 bottles ink. 【Adjustable Desing】: Math Roller Stamp has 10 different ways to queue, and you can change the calculation questions with just the turn of a button, save you more time. 【Reusable Teaching Stamp】The digital teaching stamp roller is easy to refill the ink and a transparent storage box prevents ink from spilling. The ink can be refilled with 2-3 drops on the side of the roller stamp when it runs out of ink and wait a few minutes for the ink to absorb before continuing to use.Small and exquisite, easy to carry, The imprint is clear, the color does not fade after drying, and it is not easy to smudge. 【Perfect Educational Gifts for Kids】This is a great gift, when children need to practice math problems, parents can quickly prepare them for them, and children can also prepare for each other and learn together.