The Circle cross-section may be found in the Type dropdown menu. The Circle cross-section places a circle of set diameter at the established location along a body or wing. Note that changing from a cross-section with different height and width to a circle will set the circle diameter to the average of these values. A Circle of zero diameter will collapse the cross-section to a point and can be used to close a component. In this case, it is better practice to simply change the section type to Point.