Various size pans have varying numbers of the round, semi-globular holes in them.
Street vendors making kanom krok for sale to passers-by or office workers will often have many large ones they work with.
To use, you put the pan put on top of a heat source, heat, oil the cavities, and then fill the cavities with batter to cook.
You then cover the batter while it is cooking. Some cooks use one large lid for the whole pan; others use small separate lids for each cavity.
Kanom krok pans are very similar to the Danish aebleskiver pans.
Toy versions of the pans with small holes are made for girls to play with. They use them over sterno cans as the heat source.
For more information on the use of the pans, see the entry on kanom krok.
Many theories abound about Danish missionaries bringing the idea for such a pan back to Denmark, or conversely, taking the idea to Thailand.