This set allows children to practise addition and subtraction from 0-20. These vibrant dominoes are colour coded, helping to develop colour recognition and pattern skills. Addition dominoes are blue and Subtraction dominoes are purple. Dominoes are manufactured from FSC® certified beech wood and each measure 3.7" x 1.3". Easy to clean with a dry or slightly damp cloth with mild soap or detergent, and then wipe dry. Contains 20 addition and 20 subtraction dominoes. 40 pieces total. Ages 2 and up.