To solve clogging problem occurred on conventional tundish upper nozzle and submerged entry nozzle, Horton developed porous upper nozzle serial products including fast-change type and normal type. The replacement of SEN may be done during casting when using Horton serial fast change porous upper nozzles, and longer tundish casting sequence is obtained. Horton has offered porous upper nozzles to a decade of steelworks, gaining high customer satisfaction.