The Dometic 31377 Switch is a replacement sail switch for select Atwood Everest Series Furnaces. The sail switch acts as a safety device, making sure there is no propane flow without air flow. Replaces AT35050, AT35052, AT35137, & AT37716.Also associated with the following Model Series: 85XX-II/III/IV & LD; 1522 & 2334 2-Stage; 89XX-I/II/III & LD; 2540 2-Stage. | Dometic / Atwood 31377 Hydro Flame Low Air Flow Sail Switch