We manufacture Toroidal and EI Autotransformers. An Autotransformer is smaller than a Transformer, approximately the half size and weight. Except of the dimensions and weight the mainly diferrence is that an autotransformer has one winding for both input and output . Same winding means no isolation .
An autotransformer is an economic solution for use in applications in which is not necessary the isolation.
A classic autotransformer is with input 230V and output 115V for appliances.