Operating as a constant voltage power supply, the 105 is very simple to use. The adjustment knob and hi–lo range switch control the output, which is variable in 10-volt increments from 20 to 250 volts. One, two-position switch toggles the bright LED display from indicating output voltage to output current. The 105 is equipped with an over current detector for maximum safety. Like all Thermo products, the 105 is protected by our four-year warranty.