This model is Radiotone Double Wound Isolated Enclosed type Variable Autotransformer (colloquially known as Variac) with primary / secondary Termination. It can also be provided with Ammeter/Voltmeter.
Radiotone Double Wound Isolated Enclosed type Variable Autotransformers are ideally suited for Test benches where sensitive electronic equipment are used.
Models : 0-230v, 4A, 6A, 8A, 15A.