The ET-1964 is another device apparently built for internal use at HP and not listed in any catalogs that I know of. It is a metered Variac in a Clement Cabinet with fixed line voltage (fused at 10 A, on the left side of the unit) and 0~140 V variable AC (fused at 6.25 A, on the right side) NEMA 5-15 receptacles on the front panel. Fuseholders are mounted on the front panel.

A toggle switch mounted at the top center of the front panel turns the device on or off, and the output voltage is adjusted with a large knob at the center of the panel.

The two analog meters indicate the voltage and current on the 'variable' AC receptacle. The output voltmeter reads 0 to 150 V AC, and the ammeter defaults to 7.5 A full scale; a momentary pushbutton below the variac adjustment knob opens the shunt across the meter and increases its sensitivity to 1 A full scale.