Vintage General Radio Variac W5MT Autotransformer 0-130 Variable AC Power

This is part of a family members estate and is in untested and unknown condition. When plugged in it makes a humming sound. Per Google lens: This is a vintage General Radio Company Type W5MT Variac autotransformer designed to vary AC voltage from 0 to 135 volts.The unit is rated for a 115-volt input, 50-60 cycle frequency, and a maximum current of 5 amps.It features a large black control knob for manual adjustment and a red "reset" button on the top right of the faceplate.Often used for testing electronic equipment, this device allows for the gentle warming up of antique radios or lowering voltage for guitar amplifiers. All items are sold in as-is condition without any warranties expressed or implied.