Feature: 1. Engraving Symbol: The plus minus signs on the surface of the math dices are engraved, and the symbols on the dices will not be worn or will not fade. 2. Plastic Material: These math operation dices is made of premium plastic material, which is not easy to break during playing and can be used for a long time. 3. Develop Intelligence: With the math dice set, children's intelligence can be better developed, so this math dice set is very applicable to infant education. 4. Learn Mathematics Better: Using these teaching props in class can increase children's interest in learning mathematics, and let them participate in mathematical operations. 5. An Educational Toy: Children not only have fun with these math plus minus sign dices, also can better master mathematical knowledge, which can be a perfect toy for kids. Specification: Item Type: Math dice set Material: Plastic Weight: Approx. 90g/3.2oz Product Size: 1.6x1.6x1.6cm/0.6x0.6x0.6in Applicable: Mathematics teaching. Package List: 20 x Dice Note: 1. Please allow 1‑3mm error for manual measurement, thank you!2. Due to the difference between different monitors, the pictures may not reflect the actual color of the items.3. Children should use the dices under the care of their parents.