Four in One Mathematical and Arithmetic Practice Tool: With this "Rolling Seal", you can easily assign homework to your child (including multiplication, addition exercises, division, and mathematical subtraction) Random mathematical problems: You only need to rotate the steering wheel, assign random problems, and print them on paper; 3-6. Classroom Mathematics 1x1 Calculation Training Printing is clear enough. Ink can be used on most and is not easily faded; (Recommended to use on the back of discarded files, please save paper) Number limit is 100, plus and minus signs, one-time use or sharing Reusable: The included ink can be refilled with the 'Mathe Problem Roller Stamp'. You can put it in the child's stationery box Surprise the children: this will be a unique gift for the boys and girls who are about to start school; Help elementary school students improve their math grades; Enhance attention, clothing , cool school supplies Color: Blue & Pink Material: plastic Package Contents: 4 x Roll Stamp Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.