Feature: 1. Surface Text: The text on the surface of the dice is numbers, and the numbers on the dice will not wear out and are durable. 2. Develop Intelligence: A hands on way to practice basic math skills. Develop children's intelligence for early childhood education. 3. Plastic Material: The positive and negative number dice is made of plasric, which is waterproof and wear resistant, and can be used for a long time. 4. Math Teaching: You can practice advanced math calculations using both positive and negative numbers. 5. Good Workmanship: Exquisite workmanship, beautiful appearance, small and portable size, providing you great using experience. Specification: Item Type: Dice Product Material: Plastic Color: Black and White Weight: Approx. 92g / 3.2oz Application: Math Teaching Product Size: Approx. 1.6x1.6x1.6cm / 0.6x0.6x0.6in. Package List: 20 x Dice Note: 1. Please allow 1‑3cm error due to manual measurement. Thanks for your understanding. 2. Monitors are not calibrated same, item color displayed in photos may be showing slightly different from the real object. Please take the real one as standard.