Ribs are to clay what brushes are to paint -- they move the medium. Only more. They also achieve form, control surface, compress and stabilize clay, and allow for reproducibility. Outside of your hands, they are the most powerful tool that the clay artist, and especially the potter, has available to them (with the exception of the wheel for those who throw).

Production potters have specific ribs for specific forms that they produce in quantity. However, MKM ribs are designed for more general use -- plate forms, cylinders and forms derived from cylinders such as jars and vases, bowl forms, teapots, and other thrown, coiled, or slap built forms.

There is no limit to the functionality of the rib. Nonetheless, in your own repertoire of forms you will find that you use just one or two ribs per form. Plates are more easily achieved with a plate rib; large bowls use large bowl ribs for the inside, and perhaps a separate rib for the outside; large bellied forms such as jars, vases, and bottles need a cylinder rib, and then an interior rib for pushing out the walls, with a flexible rib being used on the outside.

If you are new to ribs, welcome to a whole new world of control, power, and ease of clay movement.