... you are not sure,pls inform usage high temperature Ceramic insulated alumina tube Application:Our ceramic tube are mainly used as thermal ... and electrical field,and so on Material:75% alumina, 90% alumina,95%alumina,99%alumina,99.7%alumina or Zirconia , corundum Available sizes:Dia of ... tubeorder instruction:OD,hole size,Qty of holes, content of alumina(if you are not sure,pls inform usage)