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. 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 20 x Dice