"Gilson offers five sizes of Asphalt Institute Viscometers to determine viscosity of highly viscous materials such as bitumen at 140°F (60°C). The user measures elapsed time for a fixed volume of liquid to be drawn by vacuum through the graduated capillary tube. Time is multiplied by the viscometer constant to obtain absolute viscosity. Measurement requires a minimum sample size of 3ml and a bath depth of 7in (180mm). Certificate of calibration is supplied with each viscometer. Neoprene rubber holders to fit a 2in (51mm) diameter hole are ordered separately as PTA-100. Inquire if fixed metal holders preferred. Also see stopwatches and thermometers listed elsewhere. Est. Ship Wt.: 2lb (1kg)."