alpha-beta alumina block is the compact structure formed form alpha-Al2O3 and beta-Al2O3  crystal in a most ideal proportion. It has good erosion resisting and good stability. Its feature is that when touching melting glass, it produces little concretion and bubbles. So, α-β alumina block may be widely used to the parts of touching melting glass like work pond and passage, and may be also used to the upper structure including crown.