OSM transformers from the manufacturer, Kharkiv region.

Single-phase transformers of the OSM series with a capacity of 0.063 - 30.0 kVA of the U3 design, which are connected to an alternating current network with a frequency of 50 Hz with a nominal voltage of 110-220-660 V, are intended for powering control circuits, local lighting, signaling, rectifiers and other electrical equipment. The basic voltages for which the transformers are made are 12V, 24V, 36V, 42V, 110V, 220V, 380V, 660V (it is possible to manufacture any voltage to order).
The transformers are made on a toroidal magnetic circuit, which ensures high efficiency and a low noise threshold of operation. Transformers are equipped with a mounting plate and terminal blocks at the input and output. http://www.tor-trans.com.ua/osmtrans.html