Made by Jaeger-LeCoultre of Switzerland since approximately 1937.
Originally designed as a clock which automatically wound itself with barometric pressure changes, more accurate description will describe it as winding itself by temperature change. A temperature change of only a few degrees will keep it wound for several days. The clock itself has a 15 jewel movement, in a brass and glass case, usually all gold plated, which is self-winding and generally runs for many years without any upkeep whatsoever. The only changes may be time setting and slight adjustments to speed. Many case styles were available, the most common style is a brass (gold plated) and glass case. Still available new from Jaeger LeCoultre.