Reusable Teaching StampThe addition and subtraction teaching stamp set includes 2 digital teaching stamp, It comes in a little clear plastic case for refilling the stamp. ReusableThe teaching stamp roller is ready for use (up to 200 times) when you receive it. About 5ml refill ink (for ~10,000 stamp imprint). Ink can be refilled in the stamp side when ink runs out. Quick Addition and SubtractionAddition and subtraction within 100, flexible digital adjustment, gently rolling, can efficiently and quickly print out math practice questions within 100, it is a fun and meaningful gift for your children or friends' children! A Good Tool for Children's Mathematics EducationYou can print quickly by just scrolling through the math problems, and it dries quickly. The imprint is clear, the color does not fade after drying, and it is not easy to smudge. Learning & Education GiftThis is a great gift, when children need to practice math problems, parents can quickly prepare them for them. Say goodbye to handwritten addition and subtraction,multiplication, division math problems, and use the seal to save you more time!