The Asphalt Institute Vacuum viscometer measures the viscosity of highly viscous materials according to ASTM D2171. Minimum sample volume is 3 mL. Minimum bath depth is 180 mm (7.1 in). Viscometer is calibrated (the viscometer constant is the same at all temperatures) and provided with a certificate of calibration and instruction sheet. Includes permanently attached round metal holder, for hole 51 mm (2 in) in diameter.