One size includes 1 stamp.
The size refers to the height.
Size 1 - 20 mm / 0.8 inch high - 17 mm / 0.7 inch wide
Size 2 - 30 mm / 1.2 inch high - 26 mm / 1 inch wide
All sizes are for the final product (clay piece after the cut), and not the size of the tool.