The Prewar LIONEL Type K Transformer SLATE TOP from 1938 is a vintage collectible in black cast iron and slate material. This analog control system transformer, made in the United States by Lionel, has a wattage of 150W and operates at 110V. Lionel produced the Type K transformer from 1913 to 1938. This type I version with the slate top was offered by Lionel from 1913 to 1917. This baby weighs a lot!