Carrier HH18HA599 M/R Rollout Switch L280F is a safety control device designed to protect gas-fired HVAC equipment from excessive heat and flame rollout. It works by monitoring the temperature near the burner assembly and interrupting the electrical circuit if temperatures exceed 280°F, shutting down the system to prevent unsafe operation. https://www.partshnc.com/hh18ha599-carrier-l280f-mr-rollout-switch