This CoorsTek® AD-99.5% alumina pestle is glazed completely except for the grinding surface. AD-99.5% Alumina Mortars and Pestles are recommended for precise elemental analysis because they provide minimal sample contamination. AD-99.5% Alumina is an extremely hard (9 on Mohs scale), non-absorbent, wear-resistant material. CoorsTek® porcelain & ceramic labware has excellent thermal-shock resistance. Material: 99.5% Alumina. Length: 74mm. CoorsTek® #: 60365.