The GenRad 1644A Megohm Bridge is ideally suited to measure a wide range of resistance from the insulation resistance of cables, to high-valued resistors, diodes, transistors, to voltage and temperature coefficients of resistance, to volume and surface resistivity of solids. Seven fixed test voltages are available (10 to 1000 V), although any voltage between 10 and 1000 V may be obtained using an external resistor. Resistance range of 10E+03 to 10E+15 ohms with ?1% accuracy to 10E+12 ohms (Delta R measurements to ?0.2%). Utilizes self-checking internal standards.