Features: brand new and high quality Our math stamps come in 2 styles (addition and subtraction), just scroll gently, math problems will appear in front of you, it can print out math problems efficiently-and quickly. The math roller stamp is made of durable ABS material and uses the good cuts to ensure a clear-impression every-time. Dries quickly without fading. 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. 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. 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 gift for birthdays, Christmas, Halloween, Thanksgiving and New Years. Note: Blue addition and pink subtraction with 1 bottle-ink, double head-roller stamp without-ink. Double-head roller stamp includes addition and subtraction. Specifications: Material: ABS 1/2 Size: approx 44x30x48mm/1.73x1.18x1.89 inches 3/4 Size: approx 76x64x32mm/2.99x2.52x1.26 inches Type: 1/2/3/4 Package Includes: Type: 1.1x Blue Addition Roller Stamp with 1 Bottle-Ink/2.1x Pink Subtraction Roller Stamp with 1 Bottle-Ink/3.1x Double-head Blue Addition and Subtraction Roller Stamp/4.1x Double-head Blue Addition and Subtraction Roller Stamp note: Please allow 1-2cm errors due to manual measurement. Due to the difference betweeen different monitors,the pic may not reflect the actual color of the item. Blue addition and pink subtraction with 1 bottle ink, double head-roller stamp without ink. Double head-roller stamp includes addition and subtraction.