Keithley's 6-1/2-digit Model 6517A Electrometer/High-Resistance Meter is the ultimate tool for performing high-resistance measurements. Its 1fA measurement noise, coupled with its 1kV voltage source, makes it extremely flexible for many resistance applications. In addition, its unique alternating polarity resistance method enables repeatable measurements, even in circumstances where background currents previously made measurements impossible. It also excels at all electrometer functions. Its exceptional 200Tohms input impedance in voltage measurements, its current measurement range from 1fA to 20mA, and its charge measurements from 10fC to 2 micro C, make it a very versatile product.