This type of pan looks like a cylinder with a buckle when it is put together. It consists of a flat base and a separate ring that has a latch. The latch tightens the ring so it can grip the base lightly. It is usually used when you want a cake with clean straight sides. When you are done baking, you unlatch the ring and it expands by about an inch. This lets you easily lift it from the cake and leaves the base as a handy way of carrying the cake until you are ready to plate it.