The sets 1 - 20 and 21 - 40 are sold separately on my site as well. This is a bundle of both sets.
Each card has a numeral and the Spanish word underneath plus a matching card with only the numeral you can use for quizzing. They are color coded, so 10, 20, 30, and 40 are all the same color, as are 1, 11, 21, 31, and 41. The color coding is to add a sensorial aspect so the child may remember the numbers better.