The Whirlpool W11177230 Refrigerator Rail-Mullion is a vital component that improves your refrigerator's functioning and energy efficiency. This mullion rail separates the refrigerator and freezer compartments and helps to maintain correct temperature levels by sealing the doors when closed. It works by creating an airtight seal between the doors, preventing cold air from escaping and warm air from entering, allowing your food to stay fresh for longer. The W11177230 is compatible with select Whirlpool refrigerator models and ensures a tight fit for optimal performance. By effectively closing the refrigerator compartments, this rail mullion reduces energy consumption, resulting in cheaper electricity bills and a more environmentally responsible operation.