Sail Switch 31093MC Atwood AFS MC Enterprises This replacement sail switch is designed for use with Atwood AFS Series Furnaces. It serves as an air proving device and plays a crucial role in ensuring safety by preventing ignition until it detects 75% of the motor's rpm's. By confirming the rotation speed of the combustion wheel, it guarantees the presence of a proper air and gas mixture for smooth ignition. When the switch's paddle is pressed down, it should maintain continuity. If a sail switch needs to be replaced, it is important to choose the exact same size. The most common issues with these switches include bent paddles, loose wire connections, or obstructions between the paddle and switch contact. Compatibility: Dometic Atwood Furnaces with Serial Numbers BEFORE 72498929: AFSAD12111, AFSD12111, AFSD16111, AFSD20111, AFSDA12121, AFSAD12121, AFSD16121, AFSD20121 AFSAD12131, AFSD12131, AFSD16131, AFSD20131 AFSAD12141, AFSD12141, AFSD16141, AFSD20141, AFMD16111, AFMD16121, AFMD16131, AFMD16141, AFMD16151, AFMD20111, AFMD20121, AFMD20131, AFMD20141, AFMD20151 California Proposition 65 - WARNING: Cancer and Reproductive Harm - s://.p65warnings.ca.gov/