Ceramic Tubes Material Designation: . Mullite: 3Al2O3?2SiO2 . Alumina 99.8%: 99.8% dense alumina (Al2O3) . Alumina 99.5%: 99.5% dense alumina (Al2O3) . Alumina 96%: 96.0% dense alumina (Al2O3) ODM Accepted OEM Accepted