A Models: The A models are square, top loading manual kilns. The A series are great for the beginner. B Models: These kilns are polygon, top loading manually controlled. The B model kilns offered today are equipped with Kiln-Sitter® timers. On the B models, the Cress Clean Air System (fan) pre-wiring is only available on certain sizes at an additional cost. C Models: These kilns are square top loading or front loading kilns with gray sheet steel outer skins. The kilns are usually manually controlled (see description above of the B model kilns) but are also offered with electronic controls or with the Firemate® control system.