WESA was a independent manufacturer in Switzerland, producing 13 mm gauge (scale 1:100) from 1945 - 1966. At the end of the 1950’s, they started to produce their trains also with 12 mm gauged wheels for the wider TT market.
Because of limited distribution, Wesa trains are not commonly found in the North American market. Although the first production cycle ended in the 1960’s, additional production continued under the direction of another individual. This production cycle ended in 1983. During a visit to Zurich in the late 1990’s, I was advised that Wesa was again in limited production. Their catalog at that time was a simple affair, printed on an ink-jet printer.
For a comprehensive view of Wesa in the German language, please see here.
I have a few examples of Wesa in my personal collection. Here a Swiss locomotive and two passenger cars: