The Centurion Guide Radar from Hawk Measurement Systems uses time-domain reflectometry, passing concentrated radar pulses through a rod or cable from the sensor to the material being measured. The di-electric constant of the measured material causes a change in impedance that in turn develops a wave reflection. That reflection is sent back up the probe to the sensor, where the transit time is translated into distance using time of flight and time expansion. It is able to measure extremely low dielectric (1.5) to provide precise and continuous measurement. Since pulses are directed via a guide, factors like surface turbulence, foams, pressure, dust, vacuum, vapors, temperature, dielectric constant or tank obstructions do not influence the measurement. It offers auto-calibration to any dielectric constant greater than or equal to 1.5, adjustable sensitivity and simple setup. 978/304-3000; www.hawkmeasure.com.