2 Ceramic Plugs to fit ID of a tube. Such plugs are used as heat shields. Please specify OD and ID of tube, CEC’s are available up to four inch diameter. Ceramic plugs prevent heat leakage. The plug is fitted with a Molybdenum diSilicide pin (approximately 1/2″) to help position the plug in the furnace tube. This refractory is able to withstand temperatures of 1760C. The plug has four holes pre-drilled to enable gas flow.