The Armstrong Furnace R100811-05 M/R Limit Switch is an L205F manual-reset temperature safety control designed for compatible Armstrong gas furnaces. It monitors furnace temperature and automatically interrupts the heating circuit when temperatures reach its preset 205°F limit, helping prevent overheating and potential equipment damage. The switch requires manual resetting after activ... https://www.partshnc.com/r100811-05-armstrong-furnace-limi-control-stilt