The Whirlpool W10843943 Vent Damper used to control the flow of air in a microwave ventilation system. It operate based on the pressure change, opens and closes to let out the air, and blocks the backdraft when the fan is not running. This damper help to avoid entry of bad smells and humidity in the kitchen while maintaining the quality of the air. It help to maintain the efficiency a... https://www.hnkparts.com/w10843943-whirlpool-damper