Traditional kalans come in a variety of shapes and sizes, depending on the type of fuel used. The kalans sold in local markets can use charcoal only or wood, bamboo and various parts from a coconut tree. Traditional kalans come in one piece and are made of clay. Air is supplied to the fire by holes located at the back and sides of the kalan and through the large opening at the front. Cement blocks, stones, and steel rods and racks are also commonly used to hold cooking pots above open fires.